Detection of misfolded tau protein

ABSTRACT

Methods and kits are provided for amplifying and detecting misfolded tau protein from samples, for example, from patients having tauopathies such as Alzheimer&#39;s Disease, Progressive Supranuclear Palsy, and the like.

CROSS-REFERENCE TO RELATED Aβ PLICATIONS

This application claims priority from U.S. Provisional PatentApplication No. 62/507,166, filed on May 16, 2017, the entire contentsof which are incorporated herein by reference.

BACKGROUND

Tauopathies may include, for example, Alzheimer's disease (AD),Parkinson's Disease (PD), Progressive Supranuclear Palsy (PSP),FrontoTemporal Dementia (FTD), Corticobasal degeneration (CBD), Mildcognitive impairment (MCI), Argyrophilic grain disease (AgD) TraumaticBrain Injury (TBI), Chronic Traumatic Encephalopathy (CTE), and DementiaPugilistica (DP), and the like. Misfolded tau aggregates and fibrils maybe formed and accumulate via nucleation and growth. The misfolded tauaggregates may induce cellular dysfunction and tissue damage, amongother effects.

Real time quaking-induced conversion (RT-QuiC) has been shown to causereplication of 3-repeat (3R) tau isoforms from brain homogenate andcerebrospinal fluid samples drawn from Pick disease subjects, allowingsensitive detection of this rare disease and discrimination from othertauopathies. Surprisingly, however, for more common tauopathies ofclinical importance that include misfolding of 4R tau, the efficacy ofRT-QuiC was reduced by 3 to 5 orders of magnitude, rendering itineffective and impractical for clinical and laboratory use. Suchadverse results were obtained by seeding with brain samples containingpredominant 4-repeat (4R) tau aggregates from cases of CBD, AgD, andFTDP-17, and PSP, as well as AD, a 4R+3R tauopathy. Some AD and PSPsamples gave signals above the detection limit, but the signals wereoutliers and much weaker compared to Pick disease brain samples.Additionally, the AD and PSP samples which generated weak responses werenot analyzed for contamination. The RT-QuiC analyses of 4R or 4R+3Rtauopathies in general do not appear to be significantly different fromcontrols using diseased subjects with no immunohistologically detectedtau pathology. Such controls included diagnoses of senile change (SC),cerebrovascular disease (CVD), diffuse Lewy body disease (DLBD),frontotemporal dementia with TDP-43 (FTD-TDP), and amyotrophic lateralsclerosis (ALS). In sum, RT-QuiC analyses were shown to be generallyineffective and impractical for 4R tauopathies including 4R predominantand 4R+3R mixed tauopathies.

The present application appreciates that detection of misfolded tauprotein, e.g., for diagnosis of related diseases, may be a challengingendeavor.

SUMMARY

In one embodiment, a method is provided for determining a presence orabsence in a sample of a first misfolded protein aggregate. The methodmay include performing a first protein misfolding cyclic amplification(PMCA) procedure. The first PMCA procedure may include forming a firstincubation mixture by contacting a first portion of the sample with afirst substrate protein. The first substrate protein may include 4R tauprotein. The first PMCA procedure may include conducting an incubationcycle two or more times under conditions effective to form as firstamplified, misfolded protein aggregate. Each incubation cycle mayinclude incubating the first incubation mixture effective to causemisfolding and/or aggregation of the first substrate protein in thepresence of the first misfolded protein aggregate. Each incubation cyclemay include disrupting the first incubation mixture effective to formthe first amplified, misfolded protein aggregate. The first PMCAprocedure may include determining the presence or absence in the sampleof the first misfolded protein aggregate by analyzing the firstincubation mixture for the presence or absence of the first amplified,misfolded protein aggregate. The first misfolded protein aggregate mayinclude the first substrate protein. The first amplified, misfoldedprotein aggregate may include the first substrate protein.

In another embodiment, a method is provided for determining a presenceor absence in a subject of a tauopathy corresponding to a firstmisfolded protein aggregate. The method may include providing a samplefrom the subject. The method may include performing at least a firstPMCA procedure. The first PMCA procedure may include forming a firstincubation mixture by contacting a first portion of the sample with afirst substrate protein. The first substrate protein may include a tauisoform. The first substrate protein may be subject to pathologicalmisfolding and/or aggregation in vivo to form the first misfoldedprotein aggregate. The first PMCA procedure may include conducting anincubation cycle two or more times under conditions effective to form afirst amplified, misfolded protein aggregate. Each incubation cycle mayinclude incubating the first incubation mixture effective to causemisfolding and/or aggregation of the first substrate protein in thepresence of the first misfolded protein aggregate. Each incubation cyclemay include disrupting the first incubation mixture effective to formthe first amplified, misfolded protein aggregate. The first PMCAprocedure may include determining the presence or absence in the sampleof the first misfolded protein aggregate by analyzing the firstincubation mixture for the presence or absence of the first amplified,misfolded protein aggregate. The first PMCA procedure may includedetermining the presence or absence of the tauopathy in the subjectaccording the presence or absence of the first misfolded proteinaggregate in the sample. The first misfolded protein aggregate mayinclude the first substrate protein. The first amplified, misfoldedprotein aggregate may include the first substrate protein. The methodmay provide that the tauopathy excludes Pick's disease when the firstsubstrate protein consists of monomeric 3R tau.

In one embodiment, a method is provided using capturing for determininga presence or absence in a sample of a first misfolded proteinaggregate. The method may include capturing the first misfolded proteinaggregate from the sample to form a captured first misfolded proteinaggregate. The method may include performing at least a first PMCAprocedure. The first PMCA procedure may include forming a firstincubation mixture by contacting the captured first misfolded proteinaggregate with a molar excess of a first substrate protein. The firstsubstrate protein may be subject to pathological misfolding and/oraggregation in vivo to form the first misfolded protein aggregate. Themolar excess may be greater than an amount of protein monomer includedin the captured first misfolded protein aggregate. The method mayinclude conducting an incubation cycle two or more times effective toform a first amplified, misfolded protein aggregate. Each incubationcycle may include incubating the first incubation mixture effective tocause misfolding and/or aggregation of the first substrate protein inthe presence of the captured first misfolded protein aggregate. Eachincubation cycle may include disrupting the first incubation mixtureeffective to form the first amplified, misfolded protein aggregate. Thefirst PMCA procedure may include determining the presence or absence ofthe first misfolded protein aggregate in the sample by detecting thefirst amplified, misfolded protein aggregate. The first misfoldedprotein aggregate may include the first substrate protein. The firstamplified, misfolded protein aggregate may include the first substrateprotein.

In another embodiment, a method is provided for determining a presenceor absence of a tauopathy in a subject, the tauopathy includingAlzheimer's disease (AD). The method may include providing the subject.The method may include obtaining a sample from the subject. The samplemay include one or more of: a bio-fluid, a biomaterial, a homogenizedtissue, and a cell lysate. The method may include performing at least afirst PMCA procedure. The first PMCA procedure may include forming afirst incubation mixture by contacting the sample with a first substrateprotein. The first substrate protein may include 4R tau. The first PMCAprocedure may include conducting an incubation cycle two or more timeseffective to form a first amplified, misfolded protein aggregate. Eachincubation cycle may include incubating the first incubation mixtureeffective to cause misfolding and/or aggregation of the first substrateprotein in the presence of the first misfolded protein aggregate. Eachincubation cycle may include disrupting the incubation mixture effectiveto form the first amplified, misfolded protein aggregate. The first PMCAprocedure may include determining the presence or absence in the sampleof the first misfolded protein aggregate by detecting in the firstincubation mixture the presence or absence of the first amplified,misfolded protein aggregate. The method may include determining thepresence or absence in the subject of AD according to the presence orabsence of the first misfolded protein aggregate in the sample.

In one embodiment, a method is provided for determining a presence orabsence of a tauopathy in a subject, the tauopathy including Parkinson'sdisease (PD). The method may include providing the subject. The methodmay include obtaining a sample from the subject. The sample may includeone or more of: a bio-fluid, a biomaterial, a homogenized tissue, and acell lysate. The method may include performing at least a first PMCAprocedure. The first PMCA procedure may include forming a firstincubation mixture by contacting the sample with a first substrateprotein. The first substrate protein may include 4R tau. The first PMCAprocedure may include conducting an incubation cycle two or more timeseffective to form a first amplified, misfolded protein aggregate. Eachincubation cycle may include incubating the first incubation mixtureeffective to cause misfolding and/or aggregation of the first substrateprotein in the presence of the first misfolded protein aggregate. Eachincubation cycle may include disrupting the incubation mixture effectiveto form the first amplified, misfolded protein aggregate. The first PMCAprocedure may include determining the presence or absence in the sampleof the first misfolded protein aggregate by detecting in the firstincubation mixture the presence or absence of the first amplified,misfolded protein aggregate. The method may include determining thepresence or absence in the subject of PD according to the presence orabsence of the first misfolded protein aggregate in the sample.

In another embodiment, a method is provided for determining a presenceor absence of a tauopathy in a subject, the tauopathy includingProgressive Supranuclear Palsy (PSP). The method may include providingthe subject. The method may include obtaining a sample from the subject.The sample may include one or more of: a bio-fluid, a biomaterial, ahomogenized tissue, and a cell lysate. The method may include performingat least a first PMCA procedure. The first PMCA procedure may includeforming a first incubation mixture by contacting the sample with a firstsubstrate protein. The first substrate protein may include 4R tau. Thefirst PMCA procedure may include conducting an incubation cycle two ormore times effective to form a first amplified, misfolded proteinaggregate. Each incubation cycle may include incubating the firstincubation mixture effective to cause misfolding and/or aggregation ofthe first substrate protein in the presence of the first misfoldedprotein aggregate. Each incubation cycle may include disrupting theincubation mixture effective to form the first amplified, misfoldedprotein aggregate. The first PMCA procedure may include determining thepresence or absence in the sample of the first misfolded proteinaggregate by detecting in the first incubation mixture the presence orabsence of the first amplified, misfolded protein aggregate. The methodmay include determining the presence or absence in the subject of PSPaccording to the presence or absence of the first misfolded proteinaggregate in the sample.

In one embodiment, a method is provided for determining a presence orabsence of a tauopathy in a subject, the tauopathy includingFrontoTemporal Dementia (FTD). The method may include providing thesubject. The method may include obtaining a sample from the subject. Thesample may include one or more of: a bio-fluid, a biomaterial, ahomogenized tissue, and a cell lysate. The method may include performingat least a first PMCA procedure. The first PMCA procedure may includeforming a first incubation mixture by contacting the sample with a firstsubstrate protein. The first substrate protein may include 4R tau. Thefirst PMCA procedure may include conducting an incubation cycle two ormore times effective to form a first amplified, misfolded proteinaggregate. Each incubation cycle may include incubating the firstincubation mixture effective to cause misfolding and/or aggregation ofthe first substrate protein in the presence of the first misfoldedprotein aggregate. Each incubation cycle may include disrupting theincubation mixture effective to form the first amplified, misfoldedprotein aggregate. The first PMCA procedure may include determining thepresence or absence in the sample of the first misfolded proteinaggregate by detecting in the first incubation mixture the presence orabsence of the first amplified, misfolded protein aggregate. The methodmay include determining the presence or absence in the subject of FTDaccording to the presence or absence of the first misfolded proteinaggregate in the sample.

In another embodiment, a method is provided for determining a presenceor absence of a tauopathy in a subject, the tauopathy includingCorticobasal degeneration (CBD). The method may include providing thesubject. The method may include obtaining a sample from the subject. Thesample may include one or more of: a bio-fluid, a biomaterial, ahomogenized tissue, and a cell lysate. The method may include performingat least a first PMCA procedure. The first PMCA procedure may includeforming a first incubation mixture by contacting the sample with a firstsubstrate protein. The first substrate protein may include 4R tau. Thefirst PMCA procedure may include conducting an incubation cycle two ormore times effective to form a first amplified, misfolded proteinaggregate. Each incubation cycle may include incubating the firstincubation mixture effective to cause misfolding and/or aggregation ofthe first substrate protein in the presence of the first misfoldedprotein aggregate. Each incubation cycle may include disrupting theincubation mixture effective to form the first amplified, misfoldedprotein aggregate. The first PMCA procedure may include determining thepresence or absence in the sample of the first misfolded proteinaggregate by detecting in the first incubation mixture the presence orabsence of the first amplified, misfolded protein aggregate. The methodmay include determining the presence or absence in the subject of CBDaccording to the presence or absence of the first misfolded proteinaggregate in the sample.

In one embodiment, a kit is provided for determining a presence orabsence in a sample of a first misfolded protein aggregate. The kit mayinclude a first substrate protein that may include 4R tau. The kit mayinclude an indicator of the first misfolded protein aggregate. The firstmisfolded protein aggregate may include the first substrate protein. Thefirst misfolded protein aggregate may correspond to a tauopathy. The kitmay include a buffer. The kit may include heparin. The kit may include asalt. The kit may include instructions. The instructions may direct auser to obtain the sample. The instructions may direct the user toperform at least a first PMCA procedure. The first PMCA procedure mayinclude forming a first incubation mixture by contacting a first portionof the sample with the first substrate protein, the indicator of thefirst misfolded protein aggregate, the buffer, the heparin, and thesalt. The first incubation mixture may be formed with a concentration ofone or more of: the first substrate protein of less than about 20 μM;the heparin of less than about 75 μM; the salt as NaCl of less thanabout 190 mM; and the indicator of the first misfolded protein aggregateas Thioflavin T of less than about 9.5 μM. The first PMCA procedure mayinclude conducting an incubation cycle two or more times effective toform a first amplified, misfolded protein aggregate. Each incubationcycle may include incubating the first incubation mixture effective tocause misfolding and/or aggregation of the first substrate protein inthe presence of the first misfolded protein aggregate. Each incubationcycle may include disrupting the incubation mixture effective to formthe first amplified, misfolded protein aggregate. The instructions maydirect the user to determine the presence or absence in the sample ofthe first misfolded protein aggregate by analyzing the first incubationmixture for the presence or absence of the first amplified, misfoldedprotein aggregate according to the indicator of the first misfoldedprotein aggregate.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, which are incorporated in and constitute apart of the specification, illustrate example methods and results, andare used merely to illustrate example embodiments.

FIG. 1A shows electron micrographs taken at 0 h, 5 h, 10 h, and 24 h ofincubation.

FIG. 1B is a western blot of soluble oligomeric Aβ protein aggregates.

FIG. 2A is a graph showing non-amplified amyloid formation measured byThT fluorescence as a function of time seeded by various concentrationsof synthetic soluble oligomeric Aβ protein of EXAMPLE 1.

FIG. 2B is a graph showing amplification cycle-accelerated amyloidformation measured by ThT fluorescence as a function of time seeded byvarious concentrations of synthetic soluble oligomeric Aβ protein ofEXAMPLE 1.

FIG. 3A is a graph of amyloid formation versus time, measured as afunction of ThT fluorescence labeling, showing the average kinetics ofAβ aggregation seeded by CSF from 5 representative samples from the AD,NND, and NAND groups.

FIG. 3B is a graph of the lag phase time in h for Aβ aggregation in thepresence of samples from the AD, NND, and NAND groups.

FIG. 3C is a graph showing the extent of amyloid formation obtainedafter 180 Aβ-PMCA cycles, e.g. 90 h of incubation (P90) in the presenceof CSF samples from AD, NND and NAND patients.

FIGS. 4A-D are plots of the true positive rate (sensitivity) as afunction of the false positive rate (specificity) for different cut-offpoints using the lag phase values showed in FIG. 3B for AD vs NAND (FIG.4A), AD vs NND (FIG. 4B) and AD vs All control samples (FIG. 4C). FIG.4D estimates the most reliable cut-off point for the different set ofgroup comparisons.

FIG. 5, Table 1 shows estimations of the sensitivity, specificity andpredictive value of the Aβ-PMCA test, calculated using the lag phasenumbers.

FIG. 6 is a graph of the lag phase time in h for samples obtained after300 Aβ-PMCA cycles, e.g. 150 h of incubation (P90) in the presence ofCSF samples from AD and control patients.

FIG. 7A is a western blot showing results of immunodepletion usingsynthetically prepared Aβ oligomers spiked into human CSF.

FIG. 7B is a graph showing the kinetics of Aβ aggregation seeded bycontrol and immunodepleted CSF samples.

FIG. 7C is a graph showing the kinetics of Aβ aggregation seeded bycontrol and immunodepleted CSF samples, depleted only with the Allconformational antibody.

FIG. 8A is a schematic representation of an ELISA solid phase methodemployed to capture Aβ oligomers from complex biological samples.

FIG. 8B is a schematic representation of a magnetic bead solid phasemethod employed to capture Aβ oligomers from complex biological samples.

FIG. 9, Table 2 shows the ability of specific antibodies to capture theAβ oligomers.

FIG. 10 is a graph of amyloid formation versus time showing theacceleration of Aβ aggregation by the presence of different quantitiesof synthetic oligomers spiked in human plasma.

FIG. 11 is a graph showing time to reach 50% aggregation in an Aβ-PMCAassay in the presence of plasma samples from AD patients and controls.

FIG. 12 is a western blot showing the results of amplification of Aβaggregation by cycles of incubation/sonication in the presence ofdistinct quantities of synthetic Aβ oligomers monitored by Western blotafter protease digestion.

FIG. 13A is a graph of Thioflavin T fluorescence versus time showing thedetection of αS seeds by PD-PMCA.

FIG. 13B is a graph of time to reach 50% aggregation plotted as afunction of the indicated amounts αS seeds.

FIG. 14 shows detection of αS seeds in CSF samples from human PDpatients by PD-PMCA, versus controls with Alzheimer's disease (AD) or anon-neurodegenerative disease (NND).

FIG. 15, Table 3 demonstrates the ability of different sequence orconformational antibodies to capture αS oligomers.

FIG. 16A is a schematic representation of an ELISA solid phase methodemployed to capture αS oligomers.

FIG. 16B is a schematic representation of a magnetic bead solid phasemethod employed to capture αS oligomers.

FIGS. 17A, 17B, and 17C are a series of graphs that show the results ofimmunoprecipitation/aggregation of α-Synuclein oligomers from humanblood plasma using three different α-Synuclein antibodies. FIG. 17Ashows results with antibody N-19. FIG. 17B shows results with antibody211. FIG. 17C shows results with antibody C-20.

FIGS. 18A, 18B, and 18C are a series of graphs that show the results ofdetection for αS seeds in CSF samples. FIG. 18A shows results in controlsamples. FIG. 18B shows results in PD patients. FIG. 18C shows resultsin patients with Multiple System Atrophy (MSA).

FIG. 19 is a flow chart showing the preparation and purification ofrecombinant full-length 4R tau protein.

FIG. 20A is a graph of aggregation in % according to ThT fluorescencefor various initial amounts of tau seeds and a control. The values inFIG. 20A are the mean of two replicates, with the error bars indicatingstandard deviation.

FIG. 20B is a graph of T₅₀, the time to 50% aggregation as measured byThT fluorescence versus the log of the amount of oligomeric tau seeds infmol.

FIG. 20C is a graph of aggregation followed over time by ThTfluorescence.

FIG. 20D is a graph of the relationship between the quantity of tauoligomers and the Tau-PMCA signal (time to reach 50% aggregation).

FIGS. 20E-20L are a series of graphs that display the aggregationresults based on ThT fluorescence of 8 of the conditions tested,including 4 different time points (0, 7, 14 and 30 days) with samplessubjected to freezing and thawing or not and in the presence of bufferor CSF.

FIG. 20E is a graph of aggregation based on ThT fluorescence of a firstseed preparation at 0 days.

FIG. 20F is a graph of aggregation based on ThT fluorescence of a firstseed preparation at 7 days.

FIG. 20G is a graph of aggregation based on ThT fluorescence of a firstseed preparation at 14 days.

FIG. 20H is a graph of aggregation based on ThT fluorescence of a firstseed preparation at 30 days.

FIG. 20I is a graph of aggregation based on ThT fluorescence of a secondseed preparation at 0 days.

FIG. 20J is a graph of aggregation based on ThT fluorescence of a secondseed preparation at 7 days.

FIG. 20K is a graph of aggregation based on ThT fluorescence of a secondseed preparation at 14 days.

FIG. 20L is a graph of aggregation based on ThT fluorescence of a secondseed preparation at 30 days.

FIG. 20M is a table of Tso values showing reproducibility across 16different conditions.

FIG. 20N is a graph of ThT fluorescence vs time for the tau assay seededwith 1 pm of tau, Aβ40, AB42, His αSyn, Hu αSyn, and a control with noseeds.

FIG. 21A is a graph showing ThT fluorescence at 447 h of incubation forpatients with AD, patients with MCI, patients with other tauopathies,positive controls using samples of healthy CSF spiked with synthetic Tauoligomers (12.5 fmol), negative controls of samples of healthy CSFwithout Tau seeds; and control patients with other neurologicaldiseases.

FIG. 21B shows fluorescence signals for samples from patients with AD orother tauopathies for tau-PMCA comparable to that observed in samplescontaining recombinant tau oligomers.

FIG. 22 is a graph showing aggregation % based on ThT versus time forpatients affected by AD, FTD (frontotemporal dementia), CBD(corticobasal degeneration), and PSP (progressive supranuclear palsy),versus representative CSF samples from a control.

DETAILED DESCRIPTION

Methods and kits are provided for the detection or characterization ofmisfolded tau protein in a sample, including for the determination ordiagnosis of tauopathies in a subject from which the sample is taken.Misfolded aggregates of tau proteins may be formed and accumulate. Themisfolded aggregates may induce cellular dysfunction and tissue damageamong other effects. For example, tauopathies may include those thatpredominantly regard misfolding of 4R, or misfolding of mixtures of 4Rand 3R: Alzheimer's disease (AD), Parkinson's Disease (PD), ProgressiveSupranuclear Palsy (PSP), FrontoTemporal Dementia (FTD), Corticobasaldegeneration (CBD), Mild cognitive impairment (MCI), Argyrophilic graindisease (AgD) Traumatic Brain Injury (TBI), Chronic TraumaticEncephalopathy (CTE), Dementia Pugilistica (DP), and the like.

In some embodiments, tauopathies herein may exclude Pick's disease. Insome embodiments, the tauopathies described herein may exclude thosethat predominantly regard 3R tau misfolding, e.g., Pick's disease.

The methods may include protein misfolding cyclic amplification (PMCA),which may provide ultra-sensitive detection of misfolded proteinaggregates such as tau through artificial acceleration and amplificationof the misfolding and aggregation process in vitro. The basic concept ofPMCA has been previously demonstrated experimentally for prions (Soto etal, WO 2002/04954; Estrada, et al., U.S. Pat. App. Pub. No. 20080118938,each of which is entirely incorporated herein by reference) and forother protein misfolding, such as of “Aβ” or “beta amyloid” inAlzheimer's disease and alpha synuclein in Parkinson's disease (Soto etal, WO 2016/040907, which is entirely incorporated herein by reference).However, prior to the filing date of the present document, no referencehas described PCMA for the amplification and detection of misfolded tauprotein corresponding to any tauopathy that predominantly regardsmisfolding of 4R, or that regards misfolding of 3R tau in the presenceof 4R tau, or for any tauopathy other than Pick's disease. This documentdiscloses specific examples and details which enable PMCA technology forthe detecting the presence or absence of misfolded tau aggregates, and,in various embodiments, one or more additional PMCA procedures for thedetection of other misfolded proteins such as misfolded Aβ inAlzheimer's disease and alpha synuclein in Parkinson's disease. Such oneor more additional PMCA procedures may provide discrimination among thevarious tauopathies, for example, to distinguish AD and PD from eachother and from PSP, FTD, CBD, MCI, AgD, TBI, CTE, DP, and the like.

As used herein, “Aβ” or “beta amyloid” refers to a peptide formed viasequential cleavage of the amyloid precursor protein (Aβ P). Various Aβisoforms may include 38-43 amino acid residues. The Aβ protein may beformed when Aβ P is processed by β- and/or γ-secretases in anycombination. The Aβ may be a constituent of amyloid plaques in brains ofindividuals suffering from or suspected of having AD. Various Aβisoforms may include and are not limited to Abeta40 and Abeta42. VariousAβ peptides may be associated with neuronal damage associated with AD.

As used herein, “αS” or “alpha-synuclein” refers to full-length, 140amino acid α-synuclein protein, e.g., “αS-140.” Other isoforms orfragments may include “αS-126,” alpha-synuclein-126, which lacksresidues 41-54, e.g., due to loss of exon 3; and “αS-112”alpha-synuclein-112, which lacks residue 103-130, e.g., due to loss ofexon 5. The αS may be present in brains of individuals suffering from PDor suspected of having PD. Various αS isoforms may include and are notlimited to αS-140, αS-126, and αS-112. Various αS peptides may beassociated with neuronal damage associated with PD.

As used herein, “tau” refers to proteins are the product of alternativesplicing from a single gene, e.g., MAβ T (microtubule-associated proteintau) in humans. Tau proteins include up to full-length and truncatedforms of any of tau's isoforms. Various isoforms include, but are notlimited to, the six tau isoforms known to exist in human brain tissue,which correspond to alternative splicing in exons 2, 3, and 10 of thetau gene. Three isoforms have three binding domains and the other threehave four binding domains. Misfolded tau may be present in brains ofindividuals suffering from AD or suspected of having AD, or othertauopathies that, like AD, regard misfolding in the presence of both 4Rand 3R tau isoforms. Misfolded tau may also be present in diseases thatregard misfolding of primarily 4R tau isoforms, such as progressivesupranuclear palsy (PSP), tau-dependent frontotemporal dementia (FTD),corticobasal degeneration (CBD), mild cognitive impairment (MCI),argyrophilic grain disease (AgD), and the like.

As used herein, a “misfolded protein aggregate” is a protein thatcontains in part or in full a structural conformation of the proteinthat differs from the structural conformation that exists when involvedin its typical, non-pathogenic normal function within a biologicalsystem. A misfolded protein may aggregate. A misfolded protein maylocalize in a protein aggregate. A misfolded protein may be anon-functional protein. A misfolded protein may be a pathogenicconformer of the protein. Monomeric protein compositions may be providedin native, nonpathogenic conformations without the catalytic activityfor misfolding, oligomerization, and aggregation associated with seeds(a misfolded protein oligomer capable of catalyzing misfolding underPMCA conditions). Monomeric protein compositions may be provided inseed-free form.

As used herein, “monomeric protein” refers to single protein molecules.“Soluble, aggregated misfolded protein” refers to oligomers oraggregations of monomeric protein that remain in solution. Examples ofsoluble, misfolded protein may include any number of protein monomers solong as the misfolded protein remains soluble. For example, soluble,misfolded protein may include monomers or aggregates of between 2 andabout 50 units of monomeric protein.

Monomeric and/or soluble, misfolded protein may aggregate to forminsoluble aggregates, higher oligomers, and/or tau fibrils. For example,aggregation of Aβ or tau protein may lead to protofibrils, fibrils, andeventually misfolded plaques or tangles that may be observed in AD ortauopathy subjects. “Seeds” or “nuclei” refer to misfolded protein orshort fragmented fibrils, particularly soluble, misfolded protein withcatalytic activity for further misfolding, oligomerization, andaggregation. Such nucleation-dependent aggregation may be characterizedby a slow lag phase wherein aggregate nuclei may form, which may thencatalyze rapid formation of further aggregates and larger oligomers andpolymers. The lag phase may be minimized or removed by addition ofpre-formed nuclei or seeds. Monomeric protein compositions may beprovided without the catalytic activity for misfolding and aggregationassociated with misfolded seeds. Monomeric protein compositions may beprovided in seed-free form.

As used herein, “soluble” species may form a solution in biologicalfluids under physiological conditions, whereas “insoluble” species maybe present as precipitates, fibrils, deposits, tangles, or othernon-dissolved forms in such biological fluids under physiologicalconditions. Such biological fluids may include, for example, fluids, orfluids expressed from one or more of: amniotic fluid; bile; blood;cerebrospinal fluid; cerumen; skin; exudate; feces; gastric fluid;lymph; milk; mucus, e.g. nasal secretions; mucosal membrane, e.g., nasalmucosal membrane; peritoneal fluid; plasma; pleural fluid; pus; saliva;sebum; semen; sweat; synovial fluid; tears; urine; and the like.Insoluble species may include, for example, fibrils of Aβ, αS, 4R tau,3R tau, combinations thereof such as 3R tau+4R tau, and the like. Aspecies that dissolves in a non-biological fluid but not one of theaforementioned biological fluids under physiological conditions may beconsidered insoluble. For example, fibrils of Aβ, αS, 4R tau, 3R tau,combinations thereof such as 3R tau+4R tau, and the like may bedissolved in a solution of, e.g., a surfactant such as sodium dodecylsulfate (SDS) in water, but may still be insoluble in one or more of thementioned biological fluids under physiological conditions.

In some embodiments, the sample may exclude insoluble species of themisfolded proteins such as Aβ, αS, 4R tau, 3R tau, combinations thereofsuch as 3R tau+4R tau and the like as a precipitate, fibril, deposit,tangle, plaque, or other form that may be insoluble in one or more ofthe described biological fluids under physiological conditions.

For example, in some embodiments, the sample may exclude tau in fibrilform. The sample may exclude misfolded tau proteins in insoluble form,e.g., the sample may exclude the misfolded tau proteins as precipitates,fibrils, deposits, tangles, plaques, or other insoluble forms, e.g., infibril form. The methods described herein may include preparing thesample by excluding the misfolded protein in insoluble form, e.g., byexcluding from the sample the misfolded tau protein as precipitates,fibrils, deposits, tangles, plaques, or other insoluble forms, e.g., infibril form. The kits described herein may include instructionsdirecting a user to prepare the sample by excluding from the sample themisfolded tau protein as precipitates, fibrils, deposits, tangles,plaques, or other insoluble forms, e.g., in fibril form. The exclusionof such insoluble forms of the described misfolded proteins from thesample may be substantial or complete.

As used herein, aggregates of misfolded protein refer to non-covalentassociations of protein including soluble, misfolded protein. Aggregatesof misfolded protein may be “de-aggregated”, or disrupted to break up orrelease soluble, misfolded protein. The catalytic activity of acollection of soluble, misfolded protein seeds may scale, at least inpart with the number of such seeds in a mixture. Accordingly, disruptionof aggregates of misfolded protein in a mixture to release misfoldedprotein seeds may lead to an increase in catalytic activity foroligomerization or aggregation of monomeric protein.

In various embodiments, a method is provided for determining a presenceor absence in a sample of a first misfolded protein aggregate. Themethod may include performing a first protein misfolding cyclicamplification (PMCA) procedure. The first PMCA procedure may includeforming a first incubation mixture by contacting a first portion of thesample with a first substrate protein. The first substrate protein mayinclude 4R tau protein. The first PMCA procedure may include conductingan incubation cycle two or more times under conditions effective to formas first amplified, misfolded protein aggregate. Each incubation cyclemay include incubating the first incubation mixture effective to causemisfolding and/or aggregation of the first substrate protein in thepresence of the first misfolded protein aggregate. Each incubation cyclemay include disrupting the first incubation mixture effective to formthe first amplified, misfolded protein aggregate. The first PMCAprocedure may include determining the presence or absence in the sampleof the first misfolded protein aggregate by analyzing the firstincubation mixture for the presence or absence of the first amplified,misfolded protein aggregate. The first misfolded protein aggregate mayinclude the first substrate protein. The first amplified, misfoldedprotein aggregate may include the first substrate protein.

In various embodiments, a method is provided for determining a presenceor absence in a subject of a tauopathy corresponding to a firstmisfolded protein aggregate. The method may include providing a samplefrom the subject. The method may include performing at least a firstPMCA procedure. The first PMCA procedure may include forming a firstincubation mixture by contacting a first portion of the sample with afirst substrate protein. The first substrate protein may include a tauisoform. The first substrate protein may be subject to pathologicalmisfolding and/or aggregation in vivo to form the first misfoldedprotein aggregate. The first PMCA procedure may include conducting anincubation cycle two or more times under conditions effective to form afirst amplified, misfolded protein aggregate. Each incubation cycle mayinclude incubating the first incubation mixture effective to causemisfolding and/or aggregation of the first substrate protein in thepresence of the first misfolded protein aggregate. Each incubation cyclemay include disrupting the first incubation mixture effective to formthe first amplified, misfolded protein aggregate. The first PMCAprocedure may include determining the presence or absence in the sampleof the first misfolded protein aggregate by analyzing the firstincubation mixture for the presence or absence of the first amplified,misfolded protein aggregate. The first PMCA procedure may includedetermining the presence or absence of the tauopathy in the subjectaccording the presence or absence of the first misfolded proteinaggregate in the sample. The first misfolded protein aggregate mayinclude the first substrate protein. The first amplified, misfoldedprotein aggregate may include the first substrate protein. The methodmay provide that the tauopathy excludes Pick's disease when the firstsubstrate protein consists of monomeric 3R tau.

In various embodiments, a method is provided using capturing fordetermining a presence or absence in a sample of a first misfoldedprotein aggregate. The method may include capturing the first misfoldedprotein aggregate from the sample to form a captured first misfoldedprotein aggregate. The method may include performing at least a firstPMCA procedure. The first PMCA procedure may include forming a firstincubation mixture by contacting the captured first misfolded proteinaggregate with a molar excess of a first substrate protein. The firstsubstrate protein may be subject to pathological misfolding and/oraggregation in vivo to form the first misfolded protein aggregate. Themolar excess may be greater than an amount of protein monomer includedin the captured first misfolded protein aggregate. The method mayinclude conducting an incubation cycle two or more times effective toform a first amplified, misfolded protein aggregate. Each incubationcycle may include incubating the first incubation mixture effective tocause misfolding and/or aggregation of the first substrate protein inthe presence of the captured first misfolded protein aggregate. Eachincubation cycle may include disrupting the first incubation mixtureeffective to form the first amplified, misfolded protein aggregate. Thefirst PMCA procedure may include determining the presence or absence ofthe first misfolded protein aggregate in the sample by detecting thefirst amplified, misfolded protein aggregate. The first misfoldedprotein aggregate may include the first substrate protein. The firstamplified, misfolded protein aggregate may include the first substrateprotein.

In various embodiments, a method is provided for determining a presenceor absence of a tauopathy in a subject, the tauopathy includingAlzheimer's disease (AD). The method may include providing the subject.The method may include obtaining a sample from the subject. The samplemay include one or more of: a bio-fluid, a biomaterial, a homogenizedtissue, and a cell lysate. The method may include performing at least afirst PMCA procedure. The first PMCA procedure may include forming afirst incubation mixture by contacting the sample with a first substrateprotein. The first substrate protein may include 4R tau. The first PMCAprocedure may include conducting an incubation cycle two or more timeseffective to form a first amplified, misfolded protein aggregate. Eachincubation cycle may include incubating the first incubation mixtureeffective to cause misfolding and/or aggregation of the first substrateprotein in the presence of the first misfolded protein aggregate. Eachincubation cycle may include disrupting the incubation mixture effectiveto form the first amplified, misfolded protein aggregate. The first PMCAprocedure may include determining the presence or absence in the sampleof the first misfolded protein aggregate by detecting in the firstincubation mixture the presence or absence of the first amplified,misfolded protein aggregate. The method may include determining thepresence or absence in the subject of AD according to the presence orabsence of the first misfolded protein aggregate in the sample.

In some embodiments, determining the presence or absence in the subjectof AD may include distinguishing AD from one or more additionaltauopathies by determining a signature of AD tau protein aggregate. Thesignature AD tau protein aggregate may include one or more of: one ormore AD-specific corresponding PMCA kinetic parameters of: lag phase,T₅₀, amplification rate, and amplification extent; an assay using anantibody selective for a conformational epitope of AD tau proteinaggregate; an indicator selective for AD tau protein aggregate; and aspectrum characteristic of AD tau protein aggregate.

In various embodiments, a method is provided for determining a presenceor absence of a tauopathy in a subject, the tauopathy includingParkinson's disease (PD). The method may include providing the subject.The method may include obtaining a sample from the subject. The samplemay include one or more of: a bio-fluid, a biomaterial, a homogenizedtissue, and a cell lysate. The method may include performing at least afirst PMCA procedure. The first PMCA procedure may include forming afirst incubation mixture by contacting the sample with a first substrateprotein. The first substrate protein may include 4R tau. The first PMCAprocedure may include conducting an incubation cycle two or more timeseffective to form a first amplified, misfolded protein aggregate. Eachincubation cycle may include incubating the first incubation mixtureeffective to cause misfolding and/or aggregation of the first substrateprotein in the presence of the first misfolded protein aggregate. Eachincubation cycle may include disrupting the incubation mixture effectiveto form the first amplified, misfolded protein aggregate. The first PMCAprocedure may include determining the presence or absence in the sampleof the first misfolded protein aggregate by detecting in the firstincubation mixture the presence or absence of the first amplified,misfolded protein aggregate. The method may include determining thepresence or absence in the subject of PD according to the presence orabsence of the first misfolded protein aggregate in the sample.

In some embodiments, determining the presence or absence in the subjectof PD may include distinguishing PD from one or more additionaltauopathies by determining a signature of PD tau protein aggregate. Thesignature PD tau protein aggregate may include one or more of: one ormore PD-specific corresponding PMCA kinetic parameters of: lag phase,T₅₀, amplification rate, and amplification extent; an assay using anantibody selective for a conformational epitope of PD tau proteinaggregate; an indicator selective for PD tau protein aggregate; and aspectrum characteristic of PD tau protein aggregate.

In various embodiments, a method is provided for determining a presenceor absence of a tauopathy in a subject, the tauopathy includingProgressive Supranuclear Palsy (PSP). The method may include providingthe subject. The method may include obtaining a sample from the subject.The sample may include one or more of: a bio-fluid, a biomaterial, ahomogenized tissue, and a cell lysate. The method may include performingat least a first PMCA procedure. The first PMCA procedure may includeforming a first incubation mixture by contacting the sample with a firstsubstrate protein. The first substrate protein may include 4R tau. Thefirst PMCA procedure may include conducting an incubation cycle two ormore times effective to form a first amplified, misfolded proteinaggregate. Each incubation cycle may include incubating the firstincubation mixture effective to cause misfolding and/or aggregation ofthe first substrate protein in the presence of the first misfoldedprotein aggregate. Each incubation cycle may include disrupting theincubation mixture effective to form the first amplified, misfoldedprotein aggregate. The first PMCA procedure may include determining thepresence or absence in the sample of the first misfolded proteinaggregate by detecting in the first incubation mixture the presence orabsence of the first amplified, misfolded protein aggregate. The methodmay include determining the presence or absence in the subject of PSPaccording to the presence or absence of the first misfolded proteinaggregate in the sample.

In some embodiments, determining the presence or absence in the subjectof PSP may include distinguishing PSP from one or more additionaltauopathies by determining a signature of PSP tau protein aggregate. Thesignature PSP tau protein aggregate may include one or more of: one ormore PSP-specific corresponding PMCA kinetic parameters of: lag phase,T₅₀, amplification rate, and amplification extent; an assay using anantibody selective for a conformational epitope of PSP tau proteinaggregate; an indicator selective for PSP tau protein aggregate; and aspectrum characteristic of PSP tau protein aggregate.

In various embodiments, a method is provided for determining a presenceor absence of a tauopathy in a subject, the tauopathy includingFrontoTemporal Dementia (FTD). The method may include providing thesubject. The method may include obtaining a sample from the subject. Thesample may include one or more of: a bio-fluid, a biomaterial, ahomogenized tissue, and a cell lysate. The method may include performingat least a first PMCA procedure. The first PMCA procedure may includeforming a first incubation mixture by contacting the sample with a firstsubstrate protein. The first substrate protein may include 4R tau. Thefirst PMCA procedure may include conducting an incubation cycle two ormore times effective to form a first amplified, misfolded proteinaggregate. Each incubation cycle may include incubating the firstincubation mixture effective to cause misfolding and/or aggregation ofthe first substrate protein in the presence of the first misfoldedprotein aggregate. Each incubation cycle may include disrupting theincubation mixture effective to form the first amplified, misfoldedprotein aggregate. The first PMCA procedure may include determining thepresence or absence in the sample of the first misfolded proteinaggregate by detecting in the first incubation mixture the presence orabsence of the first amplified, misfolded protein aggregate. The methodmay include determining the presence or absence in the subject of FTDaccording to the presence or absence of the first misfolded proteinaggregate in the sample.

In some embodiments, determining the presence or absence in the subjectof FTD may include distinguishing FTD from one or more additionaltauopathies by determining a signature of FTD tau protein aggregate. Thesignature FTD tau protein aggregate may include one or more of: one ormore FTD-specific corresponding PMCA kinetic parameters of: lag phase,T₅₀, amplification rate, and amplification extent; an assay using anantibody selective for a conformational epitope of FTD tau proteinaggregate; an indicator selective for FTD tau protein aggregate; and aspectrum characteristic of FTD tau protein aggregate.

In various embodiments, a method is provided for determining a presenceor absence of a tauopathy in a subject, the tauopathy includingCorticobasal degeneration (CBD). The method may include providing thesubject. The method may include obtaining a sample from the subject. Thesample may include one or more of: a bio-fluid, a biomaterial, ahomogenized tissue, and a cell lysate. The method may include performingat least a first PMCA procedure. The first PMCA procedure may includeforming a first incubation mixture by contacting the sample with a firstsubstrate protein. The first substrate protein may include 4R tau. Thefirst PMCA procedure may include conducting an incubation cycle two ormore times effective to form a first amplified, misfolded proteinaggregate. Each incubation cycle may include incubating the firstincubation mixture effective to cause misfolding and/or aggregation ofthe first substrate protein in the presence of the first misfoldedprotein aggregate. Each incubation cycle may include disrupting theincubation mixture effective to form the first amplified, misfoldedprotein aggregate. The first PMCA procedure may include determining thepresence or absence in the sample of the first misfolded proteinaggregate by detecting in the first incubation mixture the presence orabsence of the first amplified, misfolded protein aggregate. The methodmay include determining the presence or absence in the subject of CBDaccording to the presence or absence of the first misfolded proteinaggregate in the sample.

In some embodiments, determining the presence or absence in the subjectof CBD may include distinguishing CBD from one or more additionaltauopathies by determining a signature of CBD tau protein aggregate. Thesignature CBD tau protein aggregate may include one or more of: one ormore CBD-specific corresponding PMCA kinetic parameters of: lag phase,T₅₀, amplification rate, and amplification extent; an assay using anantibody selective for a conformational epitope of CBD tau proteinaggregate; an indicator selective for CBD tau protein aggregate; and aspectrum characteristic of CBD tau protein aggregate.

In further embodiments, each of the methods described herein above mayincorporate one or more of the following features. In particular, eachfeature described with reference to any protein substrate, misfoldedprotein aggregate, amplified misfolded protein aggregate, incubationmixture, PMCA procedure, portion of the sample, and the like, should beunderstood to describe, independently selected in various otherembodiments, any other protein substrate, misfolded protein aggregate,amplified misfolded protein aggregate, incubation mixture, PMCAprocedure, portion of the sample, and the like. For example, featuresdescribed for a “first” protein substrate may, in some embodiments, alsobe independently selected to describe a “second” protein substrate;features described for a “first” misfolded protein aggregate may also beindependently selected to describe a “second” misfolded proteinaggregate; features described for a “first” incubation mixture may alsobe independently selected to describe a “second” incubation mixture;features described for a “first” PMCA procedure may also beindependently selected to describe a “second” PMCA procedure; and thelike. Further, for example, features described with reference to “each”protein substrate, misfolded protein aggregate, amplified misfoldedprotein aggregate, incubation mixture, PMCA procedure, portion of thesample, and the like, should be understood to describe, independentlyselected in various other embodiments, any other enumerated element,e.g., “first,” “second,” “third,” and the like, as applied to theprotein substrate, misfolded protein aggregate, amplified misfoldedprotein aggregate, incubation mixture, PMCA procedure, portion of thesample, and the like. For example, a description with reference to “eachsubstrate protein” may be independently selected to describe and supportrecitations of a “first substrate protein,” a “second substrateprotein,” a “third substrate protein,” and the like.

In several embodiments, features described generally for enumerated orspecified elements, e.g., “first,” “second,” “each,” and the like, maybe independently selected to be the same or distinct. For example, insome embodiments, a first substrate protein may include a 4R tau and asecond substrate protein may include Aβ; a condition such as atemperature may be selected independently for a first and second PMCAprocedure, and the like. In several embodiments, some features describedgenerally for such first and second elements may be selected to be thesame, or to overlap, while other features described generally for suchfirst and second elements may be independently selected to be distinct.For example, in some embodiments, first and second portions of thesample may be the same or combined, and first and second incubationmixtures may be the same or combined, while corresponding first andsecond PMCA procedures may be conducted in parallel or in series in thecombined incubation mixture using different first and second substrateproteins, e.g., 4R tau and Aβ.

In several embodiments, one, two, or more instances may be independentlyselected for each protein substrate, misfolded protein aggregate,amplified misfolded protein aggregate, incubation mixture, PMCAprocedure, portion of the sample, and the like. For example, variousmethod embodiments may include a first PMCA procedure using 4R tau as afirst substrate protein, a second PMCA procedure using Aβ as a secondsubstrate protein, a third PMCA procedure using alpha synuclein as athird substrate protein, a fourth PMCA procedure using 3R tau as afourth substrate protein, and the like. Such multiple PMCA proceduresmay be performed for a sample, e.g., a laboratory sample, or a sampledrawn from a subject, such as a subject having a tauopathy. Suchmultiple PMCA procedures may be performed in parallel for each proteinsubstrate, misfolded protein aggregate, amplified misfolded proteinaggregate, incubation mixture, PMCA procedure, portion of the sample,and the like, for example as follows.

In various embodiments, the method may include determining the presencein the sample of the first misfolded protein aggregate. The method mayinclude performing at least a second PMCA procedure to determine thepresence or absence in the sample of at least a second misfolded proteinaggregate. The second PMCA procedure may include forming a secondincubation mixture by contacting a second portion of the sample with asecond substrate protein. The second substrate protein may be subject topathological misfolding and/or aggregation in vivo to form the secondmisfolded protein aggregate. The second PMCA procedure may includeconducting an incubation cycle two or more times under conditionseffective to form a second amplified, misfolded protein aggregate. Eachincubation cycle may include incubating the second incubation mixtureeffective to cause misfolding and/or aggregation of the second substrateprotein in the presence of the second misfolded protein aggregate. Eachincubation cycle may include disrupting the second incubation mixtureeffective to form the second amplified, misfolded protein aggregate. Thesecond PMCA procedure may include determining the presence or absence inthe sample of the second misfolded protein aggregate by analyzing thesecond incubation mixture for the presence or absence of the secondamplified, misfolded protein aggregate. The second misfolded proteinaggregate may include the second substrate protein. The secondamplified, misfolded protein aggregate may include the second substrateprotein.

In some embodiments, the method may include determining the presence inthe sample of the first misfolded protein aggregate and the secondmisfolded protein aggregate. The method may include performing at leasta third PMCA procedure to determine the presence or absence in thesample of at least a third misfolded protein aggregate. The third PMCAprocedure may include forming a third incubation mixture by contacting athird portion of the sample with a third substrate protein. The thirdsubstrate protein may be subject to pathological misfolding and/oraggregation in vivo to form the third misfolded protein aggregate. Thethird PMCA procedure may include conducting an incubation cycle two ormore times under conditions effective to form a third amplified,misfolded protein aggregate. Each incubation cycle may includeincubating the third incubation mixture effective to cause misfoldingand/or aggregation of the third substrate protein in the presence of thethird misfolded protein aggregate. Each incubation cycle may includedisrupting the third incubation mixture effective to form the thirdamplified, misfolded protein aggregate. The third PMCA procedure mayinclude determining the presence or absence in the sample of the thirdmisfolded protein aggregate by analyzing the third incubation mixturefor the presence or absence of the third amplified, misfolded proteinaggregate. The third misfolded protein aggregate may include the thirdsubstrate protein. The third amplified, misfolded protein aggregate mayinclude the third substrate protein.

In several embodiments, the method may include determining the presencein the sample of the first misfolded protein aggregate, the secondmisfolded protein aggregate, and the fourth misfolded protein aggregate.The method may include performing at least a fourth PMCA procedure todetermine the presence or absence in the sample of a fourth misfoldedprotein aggregate. The fourth PMCA procedure may include forming afourth incubation mixture by contacting a fourth portion of the samplewith a fourth substrate protein. The fourth substrate protein may besubject to pathological misfolding and/or aggregation in vivo to formthe fourth misfolded protein aggregate. The fourth PMCA procedure mayinclude conducting an incubation cycle two or more times underconditions effective to form a fourth amplified, misfolded proteinaggregate. Each incubation cycle may include incubating the fourthincubation mixture effective to cause misfolding and/or aggregation ofthe fourth substrate protein in the presence of the fourth misfoldedprotein aggregate. Each incubation cycle may include disrupting thefourth incubation mixture effective to form the fourth amplified,misfolded protein aggregate. The fourth PMCA procedure may includedetermining the presence or absence in the sample of the fourthmisfolded protein aggregate by analyzing the fourth incubation mixturefor the presence or absence of the fourth amplified, misfolded proteinaggregate. The fourth misfolded protein aggregate may include the fourthsubstrate protein. The fourth amplified, misfolded protein aggregate mayinclude the fourth substrate protein.

In various embodiments, the first substrate protein may independentlyinclude a tau isoform, e.g., 3R tau, 4R tau, and the like. In severalembodiments, the first substrate protein may include 4R tau. The firstsubstrate protein may include 3R tau. The first substrate protein mayexclude 3R tau, for example, when the sample corresponds to Pick'sdisease or is drawn from a subject having Pick's disease. The firstsubstrate protein may be soluble. The first substrate protein may bemonomeric. The first substrate protein may be in a native in vivoconformation, e.g., folded. The first substrate protein may be distinctfrom each other substrate protein.

In various embodiments, the second substrate protein may independentlyinclude one of: a tau isoform, e.g., 3R tau, 4R tau, and the like; Aβ,alpha synuclein, and the like. The second substrate protein may includeone of: 3R tau, Aβ, alpha synuclein, and the like. The second substrateprotein may include 3R tau. The second substrate protein may include Aβ.The second substrate protein may include alpha synuclein. The secondsubstrate protein may consist essentially of, or consist of, one of: 3Rtau, 4R tau, Aβ, or alpha synuclein. The second substrate protein may besoluble. The second substrate protein may be monomeric. The secondsubstrate protein may be in a native in vivo conformation, e.g., folded.The second substrate protein may be distinct from each other substrateprotein.

In various embodiments, the third substrate protein may independentlyinclude one of: a tau isoform, e.g., 3R tau, 4R tau, and the like; Aβ,alpha synuclein, and the like. The third substrate protein may includeone of: 3R tau, Aβ, alpha synuclein, and the like. The third substrateprotein may include 3R tau. The third substrate protein may include Aβ.The third substrate protein may include alpha synuclein. The thirdsubstrate protein may consist essentially of, or consist of, one of: 3Rtau, 4R tau, Aβ, or alpha synuclein. The third substrate protein may besoluble. The third substrate protein may be monomeric. The thirdsubstrate protein may be in a native in vivo conformation, e.g., folded.The third substrate protein may be distinct from each other substrateprotein.

In various embodiments, the fourth substrate protein may independentlyinclude one of: a tau isoform, e.g., 3R tau, 4R tau, and the like; Aβ,alpha synuclein, and the like. The fourth substrate protein may includeone of: 3R tau, Aβ, alpha synuclein, and the like. The fourth substrateprotein may include 3R tau. The fourth substrate protein may include Aβ.The fourth substrate protein may include alpha synuclein. The fourthsubstrate protein may consist essentially of, or consist of, one of: 3Rtau, 4R tau, Aβ, or alpha synuclein. The fourth substrate protein may besoluble. The fourth substrate protein may be monomeric. The fourthsubstrate protein may be in a native in vivo conformation, e.g., folded.The fourth substrate protein may be distinct from each other substrateprotein.

In some embodiments the sample may be taken from a subject. The methodmay include determining or diagnosing the presence or absence of atauopathy in the subject according to the presence or absence of thefirst misfolded protein aggregate in the sample.

In several embodiments, the method may include performing at least asecond PMCA procedure to determine the presence or absence in the sampleof second misfolded protein aggregate, e.g., a misfolded proteinaggregate that includes a second substrate protein. The second PMCAprocedure may include forming a second incubation mixture by contactinga second portion of the sample with a second substrate protein. Thesecond substrate protein may be subject to pathological misfoldingand/or aggregation in vivo to form the second misfolded proteinaggregate. The methods may include determining the presence or absencein the sample of the second misfolded protein aggregate by analyzing thesecond incubation mixture for the presence or absence of the secondamplified, misfolded protein aggregate. The second misfolded proteinaggregate may include the second substrate protein. The secondamplified, misfolded protein aggregate may include the second substrateprotein. The second substrate protein may include one of: amyloid-beta(Aβ), alpha synuclein, and 3R tau.

In some embodiments, the sample may be taken from a subject. The methodsmay include determining or diagnosing the presence or absence of atauopathy in the subject according to the presence or absence of thefirst misfolded protein aggregate in the sample. The methods may includeperforming at least a second PMCA procedure to determine the presence orabsence in the sample of a second misfolded protein aggregate. Thesecond PMCA procedure may include forming a second incubation mixture bycontacting a second portion of the sample with a second substrateprotein. The second substrate protein may be subject to pathologicalmisfolding and/or aggregation in vivo to form the second misfoldedprotein aggregate. The second PMCA procedure may include conducting anincubation cycle two or more times under conditions effective to form asecond amplified, misfolded protein aggregate. Each incubation cycle mayinclude incubating the second incubation mixture effective to causemisfolding and/or aggregation of the second substrate protein in thepresence of the second misfolded protein aggregate. Each incubationcycle may include disrupting the second incubation mixture effective toform the second amplified, misfolded protein aggregate. The second PMCAprocedure may include determining the presence or absence in the sampleof the second misfolded protein aggregate by analyzing the secondincubation mixture for the presence or absence of the second amplified,misfolded protein aggregate. The second misfolded protein aggregate mayinclude the second substrate protein. The second amplified, misfoldedprotein aggregate may include the second substrate protein.

In various embodiments, the subject may have the tauopathy. The methodsmay include characterizing an identity of the tauopathy in the subjectaccording to: the presence in the sample of the first misfolded proteinaggregate; and the presence or absence in the sample of the secondmisfolded protein aggregate. The second substrate protein may includeone of: amyloid-beta (Aβ), alpha synuclein, and 3R tau. For example, thepresence of misfolded 4R tau aggregate as the first misfolded proteinaggregate and Aβ as the second misfolded protein aggregate may indicatethe tauopathy in the subject is AD; the presence of misfolded 4R tauaggregate as the first misfolded protein aggregate and alpha synucleinas the second misfolded protein aggregate may indicate the tauopathy inthe subject is PD; the presence of misfolded 4R tau aggregate as thefirst misfolded protein aggregate and the absence of the secondmisfolded protein aggregate including Aβ, alpha synuclein, or 3R mayindicate a 4R tauopathy, such as PSP, CBD, AGD, and the like.

In various embodiments, the tauopathy may include a primary tauopathy ora secondary tauopathy. The tauopathy may be characterized at least inpart by misfolding and/or aggregation of 4R tau protein. The tauopathymay be characterized at least in part by misfolding and/or aggregationof 4R tau protein and 3R tau protein. The tauopathy may be characterizedat least in part by misfolded and/or aggregated 4R tau protein, in aratio to misfolded and/or aggregated 3R tau protein, of one of about:1:99, 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55,50:50, 55:45, 60:40, 65:35, 70:30, 75:25, 80:20, 85:15, 90:10, 95:5, and99:1, or a range between any two of the preceding ratios, for example,between 1:99 and 99:1.

In several embodiments, the methods may include characterizing anidentity of the tauopathy by analyzing the first amplified, misfoldedprotein aggregate or one or more corresponding PMCA kinetic parametersthereof for a signature of at least one of: Alzheimer's disease (AD),Parkinson's Disease (PD), Progressive Supranuclear Palsy (PSP),FrontoTemporal Dementia (FTD), Corticobasal degeneration (CBD), Mildcognitive impairment (MCI), Argyrophilic grain disease (AgD) TraumaticBrain Injury (TBI), Chronic Traumatic Encephalopathy (CTE), and DementiaPugilistica (DP). For example, characterizing the identity of thetauopathy may include determining the one or more corresponding PMCAkinetic parameters, including one or more of: lag phase, T₅₀,amplification rate, and amplification extent. Characterizing theidentity of the tauopathy may include comparing the one or morecorresponding PMCA kinetic parameters to one or more correspondingpredetermined corresponding PMCA kinetic parameters that arecharacteristic of the identity of the tauopathy to determine asimilarity or difference effective to characterize the identity of thetauopathy.

In some embodiments, the methods may include characterizing the identityof the tauopathy using an antibody selective for a conformationalepitope of a tauopathy-specific misfolded tau protein aggregate. Themethods may include characterizing the identity of the tauopathy usingan indicator selective for each tauopathy-specific misfolded tau proteinaggregate. The indicator selective for each tauopathy-specific misfoldedtau protein aggregate may include a small molecule, a peptide, or a DNAor RNA aptamer; and the like. The methods may include characterizing theidentity of the tauopathy using a spectrum characteristic of eachtauopathy-specific misfolded tau protein aggregate.

In some embodiments, the methods may include, for example,characterizing the identity of the tauopathy by analyzing theproteolytic resistance of each tauopathy-specific misfolded tau proteinaggregate. For example, each tauopathy-specific misfolded tau proteinaggregate may be contacted with a proteinase, e.g., proteinase K,trypsin, chymotrypsin, and the like, at a proteinase concentration offrom 0.1 to 5000 μg/mL, at various temperatures from 20° C. to 120° C.and for various times, e.g., from 1 min to 4 h. The proteolyticresistance of each tauopathy-specific misfolded tau protein aggregatemay be characterized and used to distinguish the varioustauopathy-specific misfolded tau protein aggregates.

In several embodiments, the methods may include characterizing theidentity of the tauopathy by analyzing the stability to denaturation ofeach tauopathy-specific misfolded tau protein aggregate. For example,each tauopathy-specific misfolded tau protein aggregate may be treatedwith guanidinium or urea at a sufficiently elevated temperature toinduce protein denaturation of each tauopathy-specific misfolded tauprotein aggregate. The concentration of guanidinium or urea may rangefrom 0.1 M to 8 M. The temperature may range between 20° C. to 120° C.The stability of each tauopathy-specific misfolded tau protein aggregatemay be characterized and used to distinguish the varioustauopathy-specific misfolded tau protein aggregates.

The methods may include sedimentation of each tauopathy-specificmisfolded tau protein aggregate. The methods may include gelchromatography to characterize the size of each tauopathy-specificmisfolded tau protein aggregate. The methods may include circulardichroism spectroscopy of each tauopathy-specific misfolded tau proteinaggregate. The methods may include Fourier transform infraredspectroscopy to analyze secondary structure of each tauopathy-specificmisfolded tau protein aggregate. The methods may include nuclearmagnetic resonance spectroscopy to analyze structure of eachtauopathy-specific misfolded tau protein aggregate. The methods mayinclude mass spectrometry, e.g., fragmentation and collision induceddissociation to analyze secondary and tertiary structure of eachtauopathy-specific misfolded tau protein aggregate. The methods mayinclude microscopy, e.g., atomic force microscopy, cryo-electronmicroscopy, and the like to analyze morphology of eachtauopathy-specific misfolded tau protein aggregate. Each of thesemethods may be coupled with substitution using atomic isotopes ofdifferent mass, magnetic properties, and/or isotopic stability tocomplement the methods; for example, nuclear magnetic resonancespectroscopy may be coupled with deuterium exchange in eachtauopathy-specific misfolded tau protein aggregate to obtain structuralinformation.

In various embodiments, the methods are provided such that the tauopathyspecifically excludes Pick's disease. In various embodiments, theexclusion of Pick's disease does not encompass the remainder of Pick'scomplex of diseases.

In several embodiments, the methods may include determining ordiagnosing the presence or absence of a tauopathy in the subjectincluding comparing the presence or absence of the first misfoldedprotein aggregate in the sample to a control sample taken from a controlsubject. The detecting may include detecting an amount of the firstmisfolded protein aggregate in the sample. The sample may be taken froma subject. The methods may include determining or diagnosing thepresence or absence of a tauopathy in the subject by comparing theamount of the first misfolded protein aggregate in the sample to apredetermined threshold amount. The sample may be taken from a subjectexhibiting no clinical signs of dementia according to cognitive testing.The methods may include determining or diagnosing the presence orabsence of a tauopathy in the subject according to the presence orabsence of the first misfolded protein aggregate in the sample. Thesample may be taken from a subject exhibiting no cortex plaques ortangles according to contrast imaging. The methods may includedetermining or diagnosing the presence or absence of a tauopathy in thesubject according to the presence or absence of the first misfoldedprotein aggregate in the sample. The sample may be taken from a subjectexhibiting clinical signs of dementia according to cognitive testing.The methods may include determining or diagnosing the presence orabsence of a tauopathy as a contributing factor to the clinical signs ofdementia in the subject according to the presence or absence of thefirst misfolded protein aggregate in the sample. The sample may be takenfrom a subject exhibiting no clinical signs of dementia according tocognitive testing. The subject may exhibit a predisposition to dementiaaccording to genetic testing. The genetic testing may indicate, forexample, an increased risk of tauopathy according to one or two copiesof the ApoE4 allele, variants of the brain derived neurotrophic factor(BDNF) gene, such as the val66met allele, in which valine at AA position66 is replaced by methionine, and the like. The methods may includedetermining or diagnosing the presence or absence of a tauopathy in thesubject according to the presence or absence of the first misfoldedprotein aggregate in the sample.

In some embodiments, the methods may include preparing the firstincubation mixture characterized by at least one concentration of: thefirst substrate protein of less than about 20 μM; heparin of less thanabout 75 μM; NaCl of less than about 190 mM; and Thioflavin T of lessthan about 9.5 μM.

In various embodiments, the methods may include preparing the firstincubation mixture including the first substrate protein at aconcentration in μM of one or more of about: 0.001, 0.01, 0.1, 0.25,0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5,7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14,14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, 25, 50, 70,100, 150, 200, 250, 500, 750, 1000, 1500, or 2000, or a range betweenany two of the preceding values, for example, between about 0.001 μM andabout 2000 μM. The methods may include preparing the first incubationmixture characterized by heparin at a concentration in μM of one or moreof about: 0.001, 0.01, 0.1, 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5,3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10 11, 12, 12.5, 15, 17.5, 20, 25, 30,35, 40, 45, 50, 55, 60, 65, 70, and 75, or a range between any two ofthe preceding values, for example, between about 0.001 μM and about 75μM. The methods may include preparing the first incubation mixtureincluding a buffer composition of one or more of: Tris-HCL, PBS, MES,PIPES, MOPS, BES, TES, and HEPES. The methods may include preparing thefirst incubation mixture including the buffer composition at a totalconcentration of one or more of about: 1 μM, 10 μM, 100 μM, 250 μM, 500μM, 750 μM, 1 mM, 10 mM, 100 mM, 250 mM, 500 mM, 750 mM, and 1M, or arange between any two of the preceding values, for example, betweenabout 1 μM and about 1 M. The methods may include preparing the firstincubation mixture including a salt composition at a total concentrationof one or more of: 1 μM, 10 μM, 100 μM, 250 μM, 500 μM, 750 μM, 1 mM, 10mM, 20 mM, 30 mM, 40 mM, 50 mM, 60 mM, 70 mM, 80 mM, 90 mM, 100 mM, 110mM, 120 mM, 130 mM, 140 mM, 150 mM, 160 mM, 170 mM, 180 mM, 190 mM, 200mM, 250 mM, 500 mM, 750 mM, and 1M, or a range between any two of thepreceding values, for example, between about 1 μM and about 1 M. Thesalt composition may include one or more of: NaCl and KCl.

In various embodiments, the methods may include preparing or maintainingthe first incubation mixture at a pH of one or more of about: 5, 5.5, 6,6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8,7.9, 8, 8.1, 8.2, 8.3, 8.4, 8.5, or 9, or a range between any two of thepreceding values, e.g., from about pH 5 to about pH 9.

In some embodiments, the methods may include preparing the firstincubation mixture including an indicator at a total concentration ofone or more of: 1 nM, 10 nM, 100 nM, 250 nM, 500 nM, 750 nM, 1 μM, 2 μM,3 μM, 4 μM, 5 μM, 6 μM, 7 μM, 8 μM, 9 μM, 9.5 μM, 10 μM, 25 μM, 50 μM,100 μM, 250 μM, 500 μM, 750 μM, 1 mM, or a range between any two of thepreceding values, for example, between about 1 nM and about 1 mM.

In some embodiments of the methods, the incubating may include heatingor maintaining the first incubation mixture at a temperature in ° C. ofone of: 5, 10, 15, 20, 22.5, 25, 27.5, 30, 31, 32, 33, 34, 35, 36, 37,38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 50, 55, 60, or a range betweenany two of the preceding values, for example, between about 5° C. andabout 60° C.

In several embodiments, the methods may include contacting an indicatorof the first misfolded protein aggregate to the first incubationmixture. The indicator of the first misfolded protein aggregate may becharacterized by an indicating state in the presence of the firstmisfolded protein aggregate and a non-indicating state in the absence ofthe first misfolded protein aggregate. Determining the presence of thefirst misfolded protein aggregate in the sample may include detectingthe indicating state of the indicator of the first misfolded proteinaggregate. The indicating state of the indicator and the non-indicatingstate of the indicator may be characterized by a difference influorescence. Determining the presence of the first misfolded proteinaggregate in the sample may include detecting the difference influorescence. The methods may include contacting a molar excess of theindicator of the first misfolded protein aggregate to the firstincubation mixture. The molar excess may be greater than a total molaramount of protein monomer included in the first substrate protein andthe first misfolded protein aggregate in the first incubation mixture.The indicator of the first misfolded protein aggregate may include oneor more of: a thioflavin, e.g., thioflavin T or thioflavin S; Congo Red,m-I-Stilbene, Chrysamine G, PIB, BF-227, X-34, TZDM, FDDNP, MeO-X-04,IMPY, NIAD-4, luminescent conjugated polythiophenes, a fusion with afluorescent protein such as green fluorescent protein and yellowfluorescent protein, derivatives thereof, and the like.

In various embodiments, the method may include determining an amount ofthe first misfolded protein aggregate in the sample. For example, knownamounts of in vitro, synthetic misfolded protein aggregate seeds may beadded to various portions of a biological fluid of a healthy patient,e.g., CSF. Subsequently, PMCA may be performed on the various portions.In each of the various portions, a fluorescent indicator of themisfolded protein aggregate may be added, and fluorescence may bemeasured as a function of, e.g., number of PMCA cycles, to determinevarious PMCA kinetics parameters, e.g., number of PMCA cycles to maximumfluorescence signal, number of PMCA cycles to 50% of maximumfluorescence signal, lag phase in increase of fluorescence signal, rateof increase in fluorescence signal versus PMCA cycles, and the like. Acalibration curve showing the relationship between the concentration ofsynthetic seeds added and the PMCA kinetic parameters. The kineticparameters may be measured for unknown samples and compared to thecalibration curve to determine the expected amount of seeds present in aparticular sample. Alternatively, the amount of the first misfoldedprotein aggregate in the sample may be determined by a series of knowndilutions of the sample, and PMCA of each serial dilution to determinewhether the first misfolded protein aggregate can be detected or not ina particular dilution. The amount of the first misfolded proteinaggregate in the undiluted sample can be estimated based on the knowndilution that results in no detection of the first misfolded proteinaggregate by PMCA. In another example, the amount of the first misfoldedprotein aggregate in the sample may be determined by a series of knowndilutions of the sample, and PMCA to determine a detection signal ineach serial dilution. The collected detection signals in the serialdilutions can be fit, e.g., via least squares analysis, to determinewhether the first misfolded protein aggregate can be detected or not ina particular dilution. In another example, the amount of the firstmisfolded protein aggregate in the sample may be determined by knownamounts of antibodies to the first misfolded protein aggregate.

In some embodiments, the methods may include detecting the amount of thefirst misfolded protein aggregate in the sample at a sensitivity of atleast about one or more of: 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%,79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%,93%, 94%, 95%, 96%, 97%, 98%, 99%, and 100%, e.g., at least about 70%.The methods may include detecting the amount of the first misfoldedprotein aggregate in the sample at less than about one or more of: 625,62.5, 6.25, 630 μg, 63 μg, 6.3 μg, 630 ng, 63 ng, 6.3 ng, 630 pg, 200pg, 63 pg, 6.3 pg, 630 fg, 300 fg, 200 fg, 125 fg, 63 fg, 50 fg, 30 fg,15 fg, 12.5 fg, 10 fg, 5 fg, or 2.5 fg, The methods may includedetecting the amount of the first misfolded protein aggregate in thesample at less than about one or more of: 100 nmol, 10 nmol, 1 nmol, 100pmol, 10 pmol, 1 μmol, 100 fmol, 10 fmol, 3 fmol, 1 fmol, 100 attomol,10 attomol, 5 attomol, 2 attomol, 1 attomol, 0.75 attomol, 0.5 attomol,0.25 attomol, 0.2 attomol, 0.15 attomol, 0.1 attomol, and 0.05 attomol,e.g., less than about 100 nmol. The methods may include detecting theamount of the first misfolded protein aggregate in the sample in a molarratio to the first substrate protein included by the sample. The molarratio may be less than about one or more of: 1:100, 1:10,000, 1:100,000,and 1:1,000,000, e.g., less than about 1:100. The methods may includedetermining the amount of the first misfolded protein aggregate in thesample compared to a control sample.

In several embodiments, the methods may include detecting the firstmisfolded protein aggregate in the sample with a specificity of at leastabout one or more of: 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%,80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%,94%, 95%, 96%, 97%, 98%, 99%, and 100%, e.g. at least about 70%. Themethods may include detecting the first misfolded protein aggregateincluding one or more of: a Western Blot assay, a dot blot assay, anenzyme-linked immunosorbent assay (ELISA), a fluorescent protein/peptidebinding assay, a thioflavin binding assay, a Congo Red binding assay, asedimentation assay, electron microscopy, atomic force microscopy,surface plasmon resonance, and spectroscopy. The ELISA may include atwo-sided sandwich ELISA. The spectroscopy may include one or more of:quasi-light scattering spectroscopy, multispectral ultravioletspectroscopy, confocal dual-color fluorescence correlation spectroscopy,Fourier-transform infrared spectroscopy, capillary electrophoresis withspectroscopic detection, electron spin resonance spectroscopy, nuclearmagnetic resonance spectroscopy, and Fluorescence Resonance EnergyTransfer (FRET) spectroscopy. Detecting the first misfolded proteinaggregate may include contacting the first incubation mixture with aprotease; and detecting the first misfolded protein aggregate usinganti-misfolded protein antibodies or antibodies specific for a misfoldedtau aggregate in one or more of: a Western Blot assay, a dot blot assay,and an ELISA.

In various embodiments, the methods may include providing the firstsubstrate protein in labeled form. The first substrate protein inlabeled form may include one or more of: a covalently incorporatedradioactive amino acid, a covalently incorporated, isotopically labeledamino acid, and a covalently incorporated fluorophore. The methods mayinclude detecting the first substrate protein in labeled form asincorporated into the first amplified, misfolded protein aggregate.

In some embodiments, the sample may include one or more of a bio-fluid,e.g., blood, a biomaterial, e.g., cerumen, a homogenized tissue, and acell lysate. The sample may include one or more of: amniotic fluid;bile; blood; cerebrospinal fluid; cerumen; skin; exudate; feces; gastricfluid; lymph; milk; mucus; mucosal membrane; peritoneal fluid; plasma;pleural fluid; pus; saliva; sebum; semen; sweat; synovial fluid; tears;and urine. The sample may be derived from cells or tissue of one or moreof: skin, brain, heart, liver, pancreas, lung, kidney, gastro-intestine,nerve, mucous membrane, blood cell, gland, and muscle. The methods mayinclude obtaining the sample from a subject, such as by drawing abio-fluid or biomaterial, performing a tissue biopsy, and the like. Thevolume of each portion of the sample added to a particular PMCAreaction, e,g., in fluid or homogenized form, may be a volume in μL ofone of about 5,000, 4,000, 3,000, 2,000, 1000, 900, 800, 750, 700, 650,600, 550, 500, 450, 400, 350, 300, 250, 200, 150, 125, 100, 90, 80, 70,60, 50, 40, 30, 25, 20, 15, 10, 5, or 1, or a range between any two ofthe preceding values, e.g., from about 1 μL to about 1000 μL. In someembodiments, when the sample is CSF, the amount of each portion added toa particular PMCA reaction may be a volume in μL of any of thepreceding, for example, one of about 80, 70, 60, 50, 40, 30, 25, 20, 15,or 10, or a range between any two of the preceding values, e.g., e.g.,from about 10 μL to about 80 μL, e.g., about 40 μL. In some embodiments,when the sample is plasma, the amount of each portion added to aparticular PMCA reaction may be a volume in μL of any of the preceding,for example, one of about 750, 700, 650, 600, 550, 500, 450, 400, 350,300, 250, or a range between any two of the preceding values, e.g.,e.g., from about 250 μL to about 750 μL, e.g., about 500 μL. In someembodiments, when the sample is blood, the amount of each portion addedto a particular PMCA reaction may be a volume in μL of any of thepreceding, for example, one of about 5,000, 4,000, 3,000, 2,000, 1000,900, 800, 750, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, or 200,or a range between any two of the preceding values, e.g., from about 200μL to about 1000 μL.

In several embodiments, the subject may be one of a: human, mouse, rat,dog, cat, cattle, horse, deer, elk, sheep, goat, pig, and non-humanprimate. The subject may be one or more of: at risk of a tauopathy,having the tauopathy, and under treatment for the tauopathy. The methodsmay include determining a progression or homeostasis of a tauopathy inthe subject by comparing the amount of the first misfolded proteinaggregate in the sample to an amount of the first misfolded proteinaggregate in a comparison sample taken from the subject at a differenttime compared to the sample. The subject may be treated with a tauopathymodulating therapy. The methods may include comparing the amount of thefirst misfolded protein aggregate in the sample to an amount of thefirst misfolded protein aggregate in a comparison sample. The sample andthe comparison sample may be taken from the subject at different timesover a period of time under the tauopathy modulating therapy. Themethods may include determining the subject is one of: responsive to thetauopathy modulating therapy according to a change in the firstmisfolded protein aggregate over the period of time, or non-responsiveto the tauopathy modulating therapy according to homeostasis of thefirst misfolded protein aggregate over the period of time. The methodsmay include treating the subject determined to be responsive to thetauopathy modulating therapy with the tauopathy modulating therapy. Themethods may include treating the subject with a tauopathy modulatingtherapy to inhibit production of the first substrate protein or toinhibit aggregation of the first misfolded protein aggregate.

In some embodiments, the subject may be treated with a proteinmisfolding disorder (PMD) modulating therapy. The method may includecomparing the amount of the each misfolded protein aggregate in thesample to an amount of the each misfolded protein aggregate in acomparison sample. The sample and the comparison sample may be takenfrom the subject at different times over a period of time under the eachmisfolded protein aggregate modulating therapy. The method may includedetermining or diagnosing the subject is one of: responsive to the eachmisfolded protein aggregate modulating therapy according to a change inthe each misfolded protein aggregate over the period of time, ornon-responsive to the each misfolded protein aggregate modulatingtherapy according to homeostasis of the each misfolded protein aggregateover the period of time. The method may include treating the subjectdetermined to be responsive to the each misfolded protein aggregatemodulating therapy with the each misfolded protein aggregate modulatingtherapy. For AD, for example, the PMD modulating therapy may includeadministration of one or more of: an inhibitor of BACE1 (beta-secretase1); an inhibitor of γ-secretase; and a modulator of Aβ homeostasis,e.g., an immunotherapeutic modulator of Aβ homeostasis. The Aβmodulating therapy may include administration of one or more of: E2609;MK-8931; LY2886721; AZD3293; semagacestat (LY-450139); avagacestat(BMS-708163); solanezumab; crenezumab; bapineuzumab; BIIB037; CAD106;8F5 or 5598 or other antibodies raised against Aβ globulomers, e.g., asdescribed by Barghorn et al, “Globular amyloid β-peptide₁₋₄₂ oligomer—ahomogenous and stable neuropathological protein in Alzheimer's disease”J. Neurochem., 2005, 95, 834-847, the entire teachings of which areincorporated herein by reference; ACC-001; V950; Affitrope AD02; and thelike.

For PD, for example, the PMD modulating therapy may include activeimmunization, such as PDO1A+ or PDO3A+, passive immunization such asPRX002, and the like. The PMD modulating therapy may also includetreatment with GDNF (Glia cell-line derived neurotrophic factor),inosine, Calcium-channel blockers, specifically Cav1.3 channel blockerssuch as isradipine, nicotine and nicotine-receptor agonists, GM-CSF,glutathione, PPAR-gamma agonists such as pioglitazone, and dopaminereceptor agonists, including D2/D3 dopamine receptor agonists and LRRK2(leucine-rich repeat kinase 2) inhibitors.

In several embodiments, the amount of misfolded protein may be measuredin samples from patients using PMCA. Patients with elevated misfoldedprotein measurements may be treated with disease modifying therapies fora PMD. Patients with normal misfolded protein measurements may not betreated. A response of a patient to disease-modifying therapies may befollowed. For example, misfolded protein levels may be measured in apatient sample at the beginning of a therapeutic intervention. Followingtreatment of the patient for a clinical meaningful period of time,another patient sample may be obtained and misfolded protein levels maybe measured. Patients who show a change in misfolded protein levelsfollowing therapeutic intervention may be considered to respond to thetreatment. Patients who show unchanged misfolded protein levels may beconsidered non-responding. The methods may include detection ofmisfolded protein aggregates in patient samples containing componentsthat may interfere with the PMCA reaction.

In various embodiments, the methods may include selectivelyconcentrating the first misfolded protein aggregate in one or more ofthe sample and the first incubation mixture. The selectivelyconcentrating the first misfolded protein aggregate may includepre-treating the sample prior to forming the first incubation mixture.The selectively concentrating the first misfolded protein aggregate mayinclude pre-treating the first incubation mixture prior to incubatingthe first incubation mixture. The selectively concentrating the firstmisfolded protein aggregate may include contacting one or moreantibodies capable of binding the first misfolded protein aggregate toform a captured first misfolded protein aggregate. The one or moreantibodies capable of binding the first misfolded protein aggregate mayinclude one or more of: an antibody specific for an amino acid epitopesequence of the first misfolded protein aggregate, and an antibodyspecific for a conformation of the first misfolded protein aggregate.The antibody specific for a conformation of the first misfolded proteinaggregate may be selective for a conformational epitope of atauopathy-specific misfolded tau aggregate. The one or more one or moreantibodies capable of binding the first misfolded protein aggregate maybe coupled to a solid phase. The solid phase may include one or more ofa magnetic bead and a multiwell plate.

For example, ELISA plates may be coated with the antibodies used tocapture first misfolded protein aggregate from the patient sample. Theantibody-coated ELISA plates may be incubated with a patient sample,unbound materials may be washed off, and the PMCA reaction may beperformed. Antibodies may also be coupled to beads. The beads may beincubated with the patient sample and used to separate first misfoldedprotein aggregate-antibody complexes from the remainder of the patientsample.

In some embodiments, contacting the sample with the first substrateprotein to form the first incubation mixture may include contacting amolar excess of the first substrate protein to the sample including thecaptured first misfolded protein aggregate. The molar excess of thefirst substrate protein may be greater than a total molar amount ofprotein monomer included in the captured first misfolded proteinaggregate. Incubating the first incubation mixture may be effective tocause misfolding and/or aggregation of the first substrate protein inthe presence of the captured first misfolded protein aggregate to formthe first amplified, misfolded protein aggregate.

In several embodiments, disrupting the first incubation mixture mayinclude physically disrupting and/or thermally disrupting. For example,the disrupting may include one or more of: sonication, stirring,shaking, freezing/thawing, laser irradiation, autoclave incubation, highpressure, and homogenization. Disrupting the first incubation mixturemay include cyclic agitation. The cyclic agitation may be conducted forone or more of: between about 50 rotations per minute (RPM) and 10,000RPM, between about 200 RPM and about 2000 RPM, and at about 500 RPM.Disrupting the first incubation mixture may be conducted in eachincubation cycle for one or more of: between about 5 seconds and about10 minutes, between about 30 sec and about 1 minute, between about 45sec and about 1 minute, and about 1 minute. Incubating the firstincubation mixture may be independently conducted, in each incubationcycle for one or more of: between about 1 minute and about 5 hours,between about 5 minutes and about 5 hours, between about 10 minutes andabout 2 hours, between about 15 minutes and about 1 hour, and betweenabout 25 minutes and about 45 minutes. Each incubation cycle may includeindependently incubating and disrupting the first incubation mixture forone or more of: incubating between about 1 minute and about 5 hours anddisrupting between about 5 seconds and about 10 minutes; incubatingbetween about 5 minutes and about 5 hours and disrupting between about 5seconds and about 10 minutes; incubating between about 10 minutes andabout 2 hours and disrupting between about 30 sec and about 1 minute;incubating between about 15 minutes and about 1 hour and disruptingbetween about 45 sec and about 1 minute; incubating between about 25minutes and about 45 minutes and disrupting between about 45 sec andabout 90 seconds; incubating for about 29 minutes and for about 1minute; and incubating about 1 minute and disrupting about 1 minute.Conducting the incubation cycle may be repeated for one or more of:between about 2 times and about 1000 times, between about 5 times andabout 500 times, between about 50 times and about 500 times, and betweenabout 150 times and about 250 times.

In various embodiments, contacting the sample with the first substrateprotein to form the first incubation mixture may be conducted underphysiological conditions. the methods may include contacting the samplewith a molar excess of the first substrate protein to form the firstincubation mixture. The molar excess may be greater than a total molaramount of protein monomer included in the first misfolded proteinaggregate in the sample.

In some embodiments, the methods may include contacting the sample witha thioflavin, e.g., thioflavin T or thioflavin S, and a molar excess ofthe first substrate protein to form the first incubation mixture. Themolar excess may be greater than an amount of the first substrateprotein included in the first misfolded protein aggregate in the sample.The method may include conducting the incubation cycle two or more timeseffective to form the first amplified, misfolded protein aggregate. Eachincubation cycle may include incubating the first incubation mixtureeffective to cause misfolding and/or aggregation of at least the portionof the first substrate protein in the presence of the first misfoldedprotein aggregate. Each incubation cycle may include shaking the firstincubation mixture effective to form the first amplified, misfoldedprotein aggregate. The methods may include determining the presence ofthe first misfolded protein aggregate in the sample by detecting afluorescence of the thioflavin corresponding to the first misfoldedprotein aggregate.

In several embodiments, the first substrate protein may be produced byone of: chemical synthesis, recombinant production, and extraction fromnon-recombinant biological samples. The first misfolded proteinaggregate may include one or more of a soluble first misfolded proteinaggregate and an insoluble first misfolded protein aggregate. The firstamplified, misfolded protein aggregate may include one or more of: asoluble portion and an insoluble portion. The first misfolded proteinaggregate may be substantially be a soluble first misfolded proteinaggregate. In some embodiments, the methods may provide that the sampleexcludes tau fibrils. For example, the sample may be filtered orcentrifuged to remove tau fibrils.

In various embodiments, the second substrate protein may be distinctfrom the first substrate protein. The second substrate protein mayinclude one of: amyloid-beta (Aβ), alpha synuclein, 3R tau, and 4R tau.The first substrate protein may include 4R tau.

In some embodiments, the methods may include performing at least asecond PMCA procedure to determine the presence or absence in the sampleof a second misfolded protein aggregate. The second PMCA procedure mayinclude forming a second incubation mixture by contacting a secondportion of the sample with a second substrate protein. The secondsubstrate protein may be subject to pathological misfolding and/oraggregation in vivo to form the second misfolded protein aggregate. Thesecond PMCA procedure may include conducting an incubation cycle two ormore times under conditions effective to form a second amplified,misfolded protein aggregate. Each incubation cycle may includeincubating the second incubation mixture effective to cause misfoldingand/or aggregation of the second substrate protein in the presence ofthe second misfolded protein aggregate. Each incubation cycle mayinclude disrupting the second incubation mixture effective to form thesecond amplified, misfolded protein aggregate. The second PMCA proceduremay include determining the presence or absence in the sample of thesecond misfolded protein aggregate by analyzing the second incubationmixture for the presence or absence of the second amplified, misfoldedprotein aggregate. The second misfolded protein aggregate may includethe second substrate protein. The second amplified, misfolded proteinaggregate may include the second substrate protein.

In several embodiments, the tauopathy may be present in the subject. Themethods may include characterizing an identity of the tauopathy in thesubject according to the presence in the sample of the first misfoldedprotein aggregate. The methods may include characterizing an identity ofthe tauopathy in the subject according to the presence or absence in thesample of the second misfolded protein aggregate.

In some embodiments, the methods may provide that that the tauopathy isnot primarily characterized by misfolding and/or aggregation of 3R tauprotein. For example, the tauopathy may be characterized at least inpart by misfolded and/or aggregated 4R tau protein, in a ratio tomisfolded and/or aggregated 3R tau protein, of one of about: 1:99, 5:95,10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45,60:40, 65:35, 70:30, 75:25, 80:20, 85:15, 90:10, 95:5, and 99:1, or arange between any two of the preceding ratios, for example, between 1:99and 99:1.

In various embodiments, the methods may include contacting the samplewith a thioflavin, e.g., thioflavin S or thioflavin T, and a molarexcess of the first substrate protein to form the first incubationmixture. The molar excess may be greater than an amount of proteinmonomer included in the first misfolded protein aggregate in the sample.The methods may include conducting the incubation cycle two or moretimes effective to form the first amplified, misfolded proteinaggregate. Each incubation cycle may include incubating the firstincubation mixture effective to cause misfolding and/or aggregation ofat least the portion of the first substrate protein in the presence ofthe first misfolded protein aggregate. Each incubation cycle may includeshaking the first incubation mixture effective to form the firstamplified, misfolded protein aggregate. The methods may includedetermining the presence or absence of the first misfolded proteinaggregate in the sample by detecting a fluorescence of the thioflavincorresponding to the first misfolded protein aggregate.

In some embodiments of the methods, the capturing the first misfoldedprotein aggregate from the sample to form a captured first misfoldedprotein aggregate may be conducted using one or more antibodies specificfor the first misfolded protein aggregate. The one or more antibodiesspecific for the first misfolded protein aggregate may include one ormore of: an antibody specific for an amino acid epitope sequence of thefirst misfolded protein aggregate and an antibody specific for aconformation of the first misfolded protein aggregate. The antibodyspecific for a conformation of the first misfolded protein aggregate maybe selective for a conformational epitope of a tauopathy-specific firstmisfolded protein aggregate. The antibody specific for the conformationof the first misfolded protein aggregate may correspond to one of:Alzheimer's disease (AD), Parkinson's Disease (PD), ProgressiveSupranuclear Palsy (PSP), FrontoTemporal Dementia (FTD), Corticobasaldegeneration (CBD), Mild cognitive impairment (MCI), Argyrophilic graindisease (AgD) Traumatic Brain Injury (TBI), Chronic TraumaticEncephalopathy (CTE), and Dementia Pugilistica (DP). The one or moreantibodies specific for the first misfolded protein aggregate may becoupled to a solid phase. The solid phase may include one or more of amagnetic bead and a multiwell plate. Contacting the sample with thefirst substrate protein to form the first incubation mixture may includecontacting a molar excess of the first substrate protein to the sample.The molar excess of the first substrate protein may be greater than atotal molar amount of protein monomer included in the captured firstmisfolded protein aggregate. Incubating the first incubation mixture maybe effective to cause misfolding and/or aggregation of the firstsubstrate protein in the presence of the captured first misfoldedprotein aggregate to form the first amplified, misfolded proteinaggregate. The first substrate protein may include 4R tau protein.

In various embodiments, the methods may include performing at least asecond PMCA procedure to determine the presence or absence in the sampleof a second misfolded protein aggregate. The second PMCA procedure mayinclude forming a second incubation mixture by contacting a secondportion of the sample with a second substrate protein, the secondsubstrate protein may be subject to pathological misfolding and/oraggregation. The second PMCA procedure may include conducting anincubation cycle two or more times under conditions effective to form asecond amplified, misfolded protein aggregate. Each incubation cycle mayinclude incubating the second incubation mixture effective to causemisfolding and/or aggregation of the second substrate protein in thepresence of the second misfolded protein aggregate. Each incubationcycle may include disrupting the second incubation mixture effective toform the second amplified, misfolded protein aggregate The second PMCAprocedure may include determining the presence or absence in the sampleof the second misfolded protein aggregate by analyzing the secondincubation mixture for the presence or absence of the second amplified,misfolded protein aggregate. The tauopathy may be present in thesubject. The methods may include characterizing an identity of thetauopathy in the subject according to: the presence in the sample of thefirst misfolded protein aggregate; and the presence or absence in thesample of the second misfolded protein aggregate. The second misfoldedprotein aggregate may include the second substrate protein. The secondamplified, misfolded protein aggregate may include the second substrateprotein. The second substrate protein may be distinct from the firstsubstrate protein. The second substrate protein may include one of:amyloid-beta (Aβ), alpha synuclein, and 3R tau.

In some embodiments, the methods may include distinguishing eachtauopathy from one or more additional tauopathies by analyzing for atleast one signature of one or more misfolded aggregates eachcorresponding to one of Aβ, alpha synuclein, and 3R tau. Each signaturemay correspond to one or more of: an assay using an antibody selectivefor a conformational epitope of any of the one or more misfoldedaggregates; an assay using an antibody selective for a conformationalepitope of any of the one or more misfolded aggregates; one or more PMCAkinetic parameters of the one or more misfolded aggregates, includingone or more of: lag phase, T₅₀, amplification rate, and amplificationextent; an indicator selective for any of the one or more misfoldedaggregates; and a spectrum characteristic of any of the one or moremisfolded aggregates.

Further, for example, specific antibodies may be employed for secondmisfolded protein aggregates. For example, for AD, amyloid antibodiesmay include one or more of: 6E10, 4G8, 82E1, A11, X-40/42, 16ADV; andthe like. Such antibodies may be obtained as follows: 6E10 and 4G8(Covance, Princeton, N.J.); 82E1 (IBL America, Minneapolis, Minn.); All(Invitrogen, Carlsbad, Calif.); X-40/42 (MyBioSource, Inc., San Diego,Calif.); and 16ADV (Acumen Pharmaceuticals, Livermore, Calif.).

Further, for PD, for example, the one or more synuclein specificantibodies may include PD specific antibodies including one or more of:α/β-synuclein N-19; α-synuclein C-20-R; α-synuclein 211; α-synuclein Syn204; α-synuclein 2B2D1; α-synuclein LB 509; α-synuclein SPM451;α-synuclein 3G282; α-synuclein 3H2897; a/β-synuclein Syn 202;a/β-synuclein 3B6; α/β/γ-synuclein FL-140; and the like. In someexamples, the one or more specific antibodies may include one or moreof: a/β-synuclein N-19; α-synuclein C-20-R; α-synuclein 211; α-synucleinSyn 204; and the like. Such antibodies may be obtained as follows:a/β-synuclein N-19 (cat. No. SC-7012, Santa Cruz Biotech, Dallas, Tex.);α-synuclein C-20-R (SC-7011-R); α-synuclein 211 (SC-12767); α-synucleinSyn 204 (SC-32280); α-synuclein 2B2D1 (SC-53955); α-synuclein LB 509(SC-58480); α-synuclein SPM451 (SC-52979); α-synuclein 3G282 (SC-69978);α-synuclein 3H2897 (SC-69977); a/β-synuclein Syn 202 (SC-32281);a/β-synuclein 3B6 (SC-69699); or α/β/γ-synuclein FL-140 (SC-10717).

In various embodiments, a kit is provided for determining a presence orabsence in a sample of a first misfolded protein aggregate. The kit mayinclude a first substrate protein that may include 4R tau. The kit mayinclude an indicator of the first misfolded protein aggregate. The firstmisfolded protein aggregate may include the first substrate protein. Thefirst misfolded protein aggregate may correspond to a tauopathy. The kitmay include a buffer. The kit may include heparin. The kit may include asalt. The kit may include instructions. The instructions may direct auser to obtain the sample. The instructions may direct the user toperform at least a first PMCA procedure. The first PMCA procedure mayinclude forming a first incubation mixture by contacting a first portionof the sample with the first substrate protein, the indicator of thefirst misfolded protein aggregate, the buffer, the heparin, and thesalt. The first incubation mixture may be formed with a concentration ofone or more of: the first substrate protein of less than about 20 μM;the heparin of less than about 75 μM; the salt as NaCl of less thanabout 190 mM; and the indicator of the first misfolded protein aggregateas Thioflavin T of less than about 9.5 μM. The first PMCA procedure mayinclude conducting an incubation cycle two or more times effective toform a first amplified, misfolded protein aggregate. Each incubationcycle may include incubating the first incubation mixture effective tocause misfolding and/or aggregation of the first substrate protein inthe presence of the first misfolded protein aggregate. Each incubationcycle may include disrupting the incubation mixture effective to formthe first amplified, misfolded protein aggregate. The instructions maydirect the user to determine the presence or absence in the sample ofthe first misfolded protein aggregate by analyzing the first incubationmixture for the presence or absence of the first amplified, misfoldedprotein aggregate according to the indicator of the first misfoldedprotein aggregate.

In several embodiments, the kit may include any element of the methodsdescribed herein. Moreover, the kit may include instructions directingthe user to conduct any of the steps of the methods described herein.

In some embodiments, for example, the instructions may include directingthe user to obtain the sample from a subject. The sample may include oneor more of: a bio-fluid, a biomaterial, a homogenized tissue, and a celllysate. The instructions directing the user to determine or diagnose atauopathy in the subject according to the presence or absence in thesample of the first misfolded protein aggregate.

In various embodiments, the kit may include a second substrate proteinand an indicator of a second misfolded protein aggregate. The secondmisfolded protein aggregate may include the second substrate protein.The second substrate protein may be distinct from the first substrateprotein. The second substrate protein may include one of: amyloid-beta(Aβ), alpha synuclein, 3R tau, and 4R tau. The instructions may directthe user to perform at least a second PMCA procedure. The second PMCAprocedure may include forming a second incubation mixture by contactinga second portion of the sample with the second substrate protein and theindicator of the second misfolded protein aggregate. The second PMCAprocedure may include conducting an incubation cycle two or more timeseffective to form a second amplified, misfolded protein aggregate. Eachincubation cycle may include incubating the second incubation mixtureeffective to cause misfolding and/or aggregation of the second substrateprotein in the presence of the second misfolded protein aggregate. Eachincubation cycle may include disrupting the incubation mixture effectiveto form the second amplified, misfolded protein aggregate. The secondPMCA procedure may include determining the presence or absence in thesample of the second misfolded protein aggregate by analyzing the secondincubation mixture for the presence or absence of the second amplified,misfolded protein aggregate. The instructions may also direct the userto characterize the sample for an identity of a tauopathy according to:the presence in the sample of the first misfolded protein aggregate; andthe presence or absence in the sample of the second misfolded proteinaggregate.

In some embodiments, the kit may include a PMCA apparatus. The PMCAapparatus may include one or more of: a multiwall microtitre plate; amicrofluidic plate; a shaking apparatus; a spectrometer; and anincubator. The apparatus may be included either as one or more of theindividual plates or apparatuses, as a combination device, and the like.For example, a shaking microplate reader may be used to perform cyclesof incubation and shaking and automatically measure the ThT fluorescenceemission during the course of an experiment (e.g., FLUOstar OPTIMA, BMGLABTECH Inc., Cary, N.C.).

The antibody specific for the conformation of the first misfoldedprotein aggregate may correspond to one of: Alzheimer's disease (AD),Parkinson's Disease (PD), Progressive Supranuclear Palsy (PSP),FrontoTemporal Dementia (FTD), Corticobasal degeneration (CBD), Mildcognitive impairment (MCI), Argyrophilic grain disease (AgD) TraumaticBrain Injury (TBI), Chronic Traumatic Encephalopathy (CTE), and DementiaPugilistica (DP). The instructions may include determining, according toa binding assay using the antibody specific for the conformation of thefirst misfolded protein aggregate, the presence or absence in thesubject of one of AD, PD, PSP, FTD, CBD, MCI, AgD, TBI, CTE, and DP.

EXAMPLES Example 1: Preparation of Synthetic Aβ Oligomers

Aβ1-42 was synthesized using solid-phase N-tert-butyloxycarbonylchemistry at the W. Keck Facility at Yale University and purified byreverse-phase HPLC. The final product was lyophilized and characterizedby amino acid analysis and mass spectrometry. To prepare stock solutionsfree of aggregated, misfolded Aβ protein, aggregates were dissolved highpH and filtration through 30 kDa cut-off filters to remove remainingaggregates. To prepare different types of aggregates, solutions ofseed-free Aβ1-42 (10 μM) were incubated for different times at 25° C. in0.1 M Tris-HCl, pH 7.4 with agitation. This preparation contained amixture of Aβ monomers as well as fibrils, protofibrils and soluble,misfolded Aβ protein in distinct proportions depending on the incubationtime. The degree of aggregation was characterized by ThT fluorescenceemission, electron microscopy after negative staining, dot blot studieswith the A11 conformational antibody and western blot after gelelectrophoresis using the 4G8 anti-Aβ antibody.

A mixture of Aβ oligomers of different sizes were generated during theprocess of fibril formation. Specifically, soluble, misfolded Aβ proteinwas prepared by incubation of monomeric synthetic Aβ1-42 (10 μM) at 25°C. with stirring. After 5 h of incubation, an abundance of soluble,misfolded Aβ protein, globular in appearance, was observed by electronmicroscopy after negative staining, with only a small amount ofprotofibrils and fibrils observed. At 10 h there are mostly protofibrilsand at 24 h, a large amount of long fibrils are observed. FIG. 1A showselectron micrographs taken at 0 h, 5 h, 10 h, and 24 h of incubation.

The soluble, misfolded Aβ protein aggregates tested positive using A11anti-oligomer specific antibody according to the method of Kayed, et al.“Common structure of soluble amyloid oligomers implies common mechanismof pathogenesis,” Science 2003, 300, 486-489. After further incubationat 10 h and 24 h, protofibrillar and fibrillar structures were observed.The size of the aggregates was determined by filtration through filtersof defined pore size and western blotting after SDS-PAGE separation.Soluble, misfolded Aβ protein formed by incubation for 5 h was retainedin filters of 30 kDa cut-off and passed through 1000 kDa cutoff filters.FIG. 1B is a western blot of soluble, misfolded Aβ protein aggregates.Electrophoretic separation of this soluble, misfolded Aβ protein showedthat the majority of the material migrated as ˜170 kDa SDS-resistantaggregates, with a minor band at 17 kDa.

Example 2: Aβ-PMCA Detects Synthetic Aβ Oligomers

EXAMPLE 2A. Seeding of Aβ aggregation was studied by incubating asolution of seed-free Aβ1-42 in the presence of Thioflavin T with orwithout different quantities of synthetic soluble, misfolded Aβ protein(Control (no oligomer); or 3, 80, 300, and 8400 femtomolar in syntheticsoluble, misfolded Aβ protein). Aβ-PMCA general procedure: Solutions of2 μM aggregate-free Aβ1-42 in 0.1 M Tris-HCl pH 7.4 (200 μL totalvolume) were placed in opaque 96-wells plates and incubated alone or inthe presence of synthetic Aβ aggregates (prepared by incubation over 5 has described in EXAMPLE 1) or 40 μL of CSF aliquots. Samples wereincubated in the presence of 5 μM Thioflavin T (ThT) and subjected tocyclic agitation (1 min at 500 rpm followed by 29 min without shaking)using an Eppendorf thermomixer, at a constant temperature of 22° C. Atvarious time points, ThT fluorescence was measured in the plates at 485nm after excitation at 435 nm using a plate spectrofluorometer. FIG. 2Ais a graph of amyloid formation (without cyclic amplification) versustime as measured by Thioflavin T fluorescence, using the indicatedfemtomolar concentration of synthetic soluble, misfolded Aβ proteinseeds. The peptide concentration, temperature and pH of the buffer weremonitored to control the extent of the lag phase and reproducibilityamong experiments. Under these conditions, no spontaneous Aβ aggregationwas detected during the time in which the experiment was performed (125h). Aggregation of monomeric Aβ1-42 protein was observed in the presenceof 0.3 to 8.4 fmol of the synthetic soluble, misfolded Aβ protein ofEXAMPLE 1.

EXAMPLE 2B: Amplification cycles, combining phases of incubation andphysical disruption were employed. The same samples as in FIG. 2A wereincubated with cyclic agitation (1 min stirring at 500 rpm followed by29 min without shaking). Aggregation was measured over time by thethioflavin T (ThT) binding to amyloid fibrils using a platespectrofluorometer (excitation: 435; emission: 485 nm). Graphs show themean and standard error of 3 replicates. The concentration of Aβoligomers was estimated assuming an average molecular weight of 170 kDa.FIG. 2B is a graph showing amplification cycle-accelerated amyloidformation measured by ThT fluorescence as a function of time for variousconcentrations of the synthetic soluble, misfolded Aβ protein ofEXAMPLE 1. Under these conditions, the aggregation of monomeric Aβ1-42protein induced by 8400, 300, 80 and 3 fmol of the synthetic soluble,misfolded Aβ protein was clearly faster and more easily distinguishedfrom that observed in the absence of the synthetic soluble, misfolded Aβprotein. This result indicates the detection limit, under theseconditions, is 3 fmol of soluble, misfolded Aβ protein or less in agiven sample.

Example 3: Aβ-PMCA Detects Misfolded Aβ in the Cerebrospinal Fluid of ADPatients

Aliquots of CSF were obtained from 50 AD patients, 39 cognitively normalindividuals affected by non-degenerative neurological diseases (NND),and 37 patients affected by non-AD neurodegenerative diseases includingother forms of dementia (NAND). Test CSF samples were obtained from 50patients with the diagnosis of probable AD as defined by the DSM-IV andthe NINCDS-ADRA guidelines (McKhann et al., 1984) and determined using avariety of tests, including routine medical examination, neurologicalevaluation, neuropsychological assessment, magnetic resonance imagingand measurements of CSF levels of Aβ1-42, total Tau and phospho-Tau. Themean age of AD patients at the time of sample collection was 71.0±8.1years (range 49-84). Control CSF samples were obtained from 39 patientsaffected by non-degenerative neurological diseases (NND), including 12cases of normal pressure hydrocephalus, 7 patients with peripheralneuropathy, 7 with diverse forms of brain tumor, 2 with ICTUS, 1 withsevere cephalgia, 3 with encephalitis, 1 with hypertension and 6 withunclear diagnosis. The mean age at which CSF samples were taken fromthis group of patients was 64.6±14.7 years (range 31-83). Control CSFsamples were also taken from 37 individuals affected by non-ADneurodegenerative diseases (NAND), including 10 cases of fronto-temporaldementia (5 behavioral and 5 language variants), 6 patients withParkinson's disease (including 4 associated with dementia and 1 withmotor neuron disease), 6 with progressive supranuclear palsy, 6 withspinocerebellar ataxia (1 associated with dementia), 4 with amyotrophiclateral sclerosis, 2 with Huntington's disease, 1 with MELAS, 1 withLewy body dementia, and 1 with vascular dementia. The mean age at samplecollection for this group was 63.8±11.1 years (range 41-80). CSF sampleswere collected in polypropylene tubes following lumbar puncture at theL4/LS or L3/L4 interspace with atraumatic needles after one nightfasting. The samples were centrifuged at 3,000 g for 3 min at 4° C.,aliquoted and stored at −80° C. until analysis. CSF cell counts, glucoseand protein concentration were determined. Albumin was measured by ratenephelometry. To evaluate the integrity of the blood brain barrier andthe intrathecal IgG production, the albumin quotient (CSF albumin/serumalbumin)×10³ and the IgG index (CSF albumin/serum albumin)/(CSFIgG/serum IgG) were calculated. The study was conducted according to theprovisions of the Helsinki Declaration and was approved by the EthicsCommittee.

The experiments as well as the initial part of the analysis wereconducted blind. FIG. 3A is a graph of amyloid formation versus time,measured as a function of ThT fluorescence labeling, showing the averagekinetics of Aβ aggregation of 5 representative samples from the AD, NND,and NAND groups.

The results indicate that CSF from AD patients significantly acceleratesAβ aggregation as compared to control CSF (P<0.001). The significance ofthe differences in Aβ aggregation kinetics in the presence of human CSFsamples was analyzed by one-way ANOVA, followed by the Tukey's multiplecomparison post-test. The level of significance was set at P<0.05. Thedifferences between AD and samples from the other two groups were highlysignificant with P<0.001 (***).

FIG. 3B is a graph of the lag phase time in h for samples from the AD,NND, and NAND groups. To determine the effect of individual samples onAβ aggregation, the lag phase was estimated, defined as the time to ThTfluorescence larger than 40 arbitrary units after subtraction of acontrol buffer sample. This value was selected considering that itcorresponds to ˜5 times the reading of the control buffer sample.

FIG. 3C is a graph showing the extent of amyloid formation obtainedafter 180 Aβ-PMCA cycles, e.g. 90 h of incubation (P90). Comparison ofthe lag phase and P90 among the experimental groups reveals asignificant difference between AD and control samples from individualswith non-degenerative neurological diseases or with non-ADneurodegenerative diseases. Further, no correlation was detected betweenthe aggregation parameters and the age of the AD patients, whichindicates that the levels of the marker corresponds to aggregated Aβprotein in patient CSF, and not patient age.

FIG. 5, Table 1 shows estimations of the sensitivity, specificity andpredictive value of the Aβ-PMCA test, calculated using the lag phasenumbers.

To study reproducibility, an experiment similar to the one shown inFIGS. 3A-C was independently done with different samples, reagents and anew batch of Aβ peptide as substrate for Aβ-PMCA. The extent of amyloidformation obtained after 300 Aβ-PMCA cycles, e.g. 150 h of incubation(P150), was measured in each patient. The control group includes bothpeople affected by other neurodegenerative diseases andnon-neurologically sick patients. Data for each sample represent theaverage of duplicate tubes. Statistical differences were analyzed bystudent-t test. FIG. 6 is a graph of the lag phase time in h for samplesobtained after 300 Aβ-PMCA cycles, e.g. 150 h of incubation (P90).

During the course of the study an entire set of CSF samples coming froma fourth location did not aggregate at all, even after spiking withlarge concentrations of synthetic oligomers. It is expected that reagentcontamination during sample collection interfered with the assay.

The differences in aggregation kinetics between different samples wereevaluated by the estimation of various different kinetic parameters,including the lag phase, A50, and P90. Lag phase is defined as the timerequired to reach a ThT fluorescence higher than 5 times the backgroundvalue of the buffer alone. The A50 corresponds to the time to reach 50%of maximum aggregation. P90 corresponds to the extent of aggregation(measured as ThT fluorescence) at 90 h. Sensitivity, specificity andpredictive value were determined using this data, with cutoff thresholdsdetermined by Receiver Operating Characteristics (ROC) curve analysis,using MedCalc software (MedCalc Software, Ostend, Belgium).

Example 4: Determination of Threshold Values of Misfolded for Aβ-PMCADetection of Ad in CSF

In support of FIG. 5, TABLE 1, sensitivity, specificity and predictivevalue were determined using the lag phase data, with cutoff thresholdsdetermined by Receiver Operating Characteristics (ROC) curve analysis,using the MedCalc software (version 12.2.1.0, MedCalc, Belgium). Asshown in FIG. 5, TABLE 1, a 90.0% sensitivity and 84.2% specificity wasestimated for the control group consisting of age-matched individualswith non-degenerative neurological diseases. By contrast, for theclinically more relevant differentiation of AD from otherneurodegenerative diseases including other forms of dementia, 100%sensitivity and 94.6% specificity was estimated. This ability of Aβ-PMCAto distinguish AD from other forms of neurodegenerative diseases isclinically significant. The overall sensitivity and specificityconsidering all control individuals was 90% and 92%, respectively.

To evaluate the performance of the Aβ-PMCA test to distinguish ADpatients from controls, the true positive rate (sensitivity) was plottedas a function of the false positive rate (specificity) for differentcut-off points. For this analysis the lag phase values for AD vs NAND(FIG. 4A), AD vs NND (FIG. 4B) and AD vs All control samples (FIG. 4C)was used. The performance of the test, estimated as the area under thecurve was 0.996±0.0033, 0.95±0.020 and 0.97±0.011 for the comparison ofAD with NAND, NND and all controls, respectively. Statistical analysiswas done using the MedCalc ROC curve analysis software (version12.2.1.0) and the result indicated that the test can distinguish AD fromthe controls with a P<0.0001. To estimate the most reliable cut-offpoint for the different set of group comparisons, sensitivity (blueline) and specificity (red line) were plotted for each cut-off value(FIG. 4D). The graph shows the curve and the 95% confidence intervalsfor the AD vs all control samples (including NAND and NND groups). Thesecut-off values were used to estimate sensitivity, specificity andpredictive value in FIG. 5, Table 1.

Example 5: Aβ-Oligomer Immunodepletion Removes Aβ Seeds in HumanCerebrospinal Fluid and Confirms Aβ-PMCA Detects Soluble Misfolded AβProtein in Ad CSF

Immunodepletion experiments were performed to confirm that Aβ-PMCAdetects a seeding activity associated to soluble, misfolded Aβ proteinpresent in CSF. The methodology for efficient immunodepletion ofsoluble, misfolded Aβ protein was first optimized by using syntheticallyprepared soluble, misfolded Aβ protein. Immunodepletion was performed byincubation with dynabeads conjugated with a mixture of antibodiesrecognizing specifically the sequence of Aβ (4G8) and conformational(A11) antibodies. FIG. 7A is a western blot showing results ofimmunodepletion using synthetically prepared Aβ oligomers spiked intohuman CSF. Soluble, misfolded Aβ protein was efficiently removed by thisimmunodepletion.

FIGS. 7A and 7B are graphs of amyloid formation versus time as measuredby Thioflavin T fluorescence, demonstrating that seeding activity in ADCSF is removed by soluble, misfolded Aβ protein immuno-depletion.Samples of AD CSF before or after immunodepletion with 4G8 and Allantibodies were used to seed Aβ aggregation in the Aβ-PMCA assay.Immunodepletion was applied to 3 AD CSF. FIG. 7B is a graph showing thekinetics of control and immunodepleted CSF samples. FIG. 7B shows thatfor immunodepleted AD CSF, the kinetics of Aβ aggregation in the Aβ-PMCAreaction was comparable to that observed in control CSF samples, andboth were significantly different from the aggregation observed with ADCSF prior to immunodepletion. FIG. 7C is a graph showing the kinetics ofcontrol and immunodepleted CSF samples, depleted only with the A11conformational antibody and aggregation monitored by Aβ-PMCA assay. FIG.7C shows similar results, obtained using AD CSF immunodepleted using theA11 conformational antibody, which specifically recognizes, misfoldedAβ. These results confirm that Aβ-PMCA detects soluble, misfolded βprotein in AD CSF.

Example 6: Solid Phase Immuno Capturing

FIGS. 8A and 8B are schematic representations of two solid phase methodsused to capture soluble, misfolded Aβ protein from complex samples suchas blood plasma. Strategy 1 employed ELISA plates pre-coated withspecific antibodies bound to a solid phase on the ELISA plate. Afterwashing the plates, the Aβ-PMCA reaction was carried out in the sameplates. Strategy 2 used magnetic beads as the solid phase coated withspecific antibodies. This approach provided concentration of thesamples.

Example 7: Specificity of Immuno Capturing

FIG. 9 shows Table 2, demonstrating the ability of specific antibodiesto capture the Aβ oligomers. The top panel shows a schematicrepresentation of the epitope recognition site on the Aβ protein of thediverse sequence antibodies used in this study. Table 2 in FIG. 9demonstrates the efficiency of different sequence or conformationalantibodies to capture Aβ oligomers. The capacity to capture oligomerswas measured by spiking synthetic Aβ oligomers in healthy human bloodplasma and detection by Aβ-PMCA. The symbols indicate that the detectionlimits using the different antibodies were: <12 fmol (+++); between10-100 fmol (++); >1 pmol (+) and not significantly higher than withoutcapturing reagent (−).

Example 8: Detection of Aβ Oligomers Spiked in Human Plasma

FIG. 10 is a graph of amyloid formation versus time as measured byThioflavin T fluorescence showing detection of soluble, misfolded Aβprotein spiked in human plasma. ELISA plates pre-coated with protein Gwere coated with an anti-conformational antibody (16ADV from Acumen).Thereafter, plates were incubated with human blood plasma (100 μl) assuch (control) or spiked with different concentrations of syntheticsoluble, misfolded Aβ protein. After incubation, plates were subjectedto Aβ-PMCA (29 min incubation and 30 s shaking) in the presence of Aβ40monomer (2 μM) and ThT (5 μM). Amyloid formation was measured byThioflavin fluorescence. FIG. 10 is representative of severalexperiments done with 3 different antibodies which worked similarly.

Example 9: Capturing of Soluble Misfolded Aβ from Ad Patient Samples VsControls

FIG. 11 is a graph showing time to reach 50% aggregation in an Aβ-PMCAassay in plasma samples from AD patients and controls. Blood plasmasamples from patients affected by AD, non-AD neurodegenerative diseases(NAD), and healthy controls were incubated with anti-Aβ antibody (82E1)coated beads. Aβ-PMCA was carried out as described in EXAMPLE 2. Thetime needed to reach 50% aggregation was recorded in individual patientsin each group. Differences were analyzed by one-way ANOVA followed bythe Tukey's post-hoc test. ROC analysis of this data showed a 82%sensitivity and 100% specificity for correctly identifying AD patientsfrom controls.

Example 10: Sonication and Shaking are Effective with Various DetectionMethods

FIG. 12 is a western blot showing the results of amplification of Aβaggregation by using sonication instead of shaking as a mean to fragmentaggregates. The experiment was done in the presence of distinctquantities of synthetic Aβ oligomers. Samples of 10 μg/ml of seed-freemonomeric Aβ1-42 were incubated alone (lane 1) or with 300 (lane 2), 30(lane 3) and 3 (lane 4) fmols of, misfolded Aβ. Samples were eitherfrozen without amplification (non-amplified) or subjected to 96 PMCAcycles (amplified), each including 30 min incubation followed by 20 secsonication. Aggregated Aβ was detected by western blot using anti-Aβantibody after treatment of the samples with proteinase K (PK). In ourexperiments, it was observed that detection using thioflavin Tfluorescence was not compatible with sonication, but works very wellwith shaking as a physical disruption method. FIG. 12 shows that using adifferent detection method for the Aβ aggregates, in this case WesternBlotting, sonication works as well as shaking.

Example 11: Production of Monomeric Aβ as PMCA Substrate

Seed-free monomeric Aβ was obtained by size exclusion chromatography.Briefly, an aliquot of a 1 mg/mL peptide solution prepared indimethylsulfoxide was fractionated using a Superdex 75 column eluted at0.5 mL/min with 10 mM sodium phosphate at pH 7.5. Peaks will be detectedby UV absorbance at 220 nm. The peak corresponding to 4-10 kDa molecularweight containing monomer/dimmers of Aβ was collected and concentrationdetermined by amino acid analysis. Samples were stored lyophilized at−80° C.

Example 12: Production and Purification of A3

E. coli cells harboring pET28 GroES-Ub-A1342 plasmid were grown in Luriabroth (LB) at 37° C., and expression was induced with 0.4 mM IPTG. After4 h, cells were harvested and lysed in a lysis buffer (20 mM Tris-Cl, pH8.0, 10 mM NaCl, 0.1 mM PMSF, 0.1 mM EDTA and 1 mM β-mercaptoethanol)and centrifuged at 18,000 rpm for 30 min. Inclusion bodies werere-suspended in a resuspension buffer (50 mM Tris-Cl, pH 8.0, 150 mMNaCl, and 1 mM DTT) containing 6 M urea. Insoluble protein was removedby centrifugation at 18,000 rpm for 30 min. The supernatant containingGroES-Ub-Aβ42 fusion protein will be collected. To cleave off Aβ42 fromfusion protein, the fusion protein was diluted 2-fold with resuspensionbuffer and treated with recombinant de-ubiquinating enzyme (Usp2cc)1:100 enzyme to substrate molar ratio at 37° C. for 2 h. After that,samples was loaded on a C18 column (25 mm×250 mm, Grace Vydac, USA).Aβ42 was purified with a solvent system buffer 1 (30 mM ammoniumacetate, pH 10, 2% acetonitrile) and buffer 2 (70% acetonitrile) at aflow rate 10 ml/min using a 20-40% linear gradient of buffer 2 over 35min. Purified Aβ42 was lyophilized and stored at −80° C., until use.

Example 13: Detection of αS Seeds by PD-PMCA

EXAMPLE 13A: Seeding of αS aggregation was studied by incubating asolution of seed-free αS in the presence of Thioflavin T with or withoutdifferent quantities of synthetic soluble oligomeric αS protein: Control(no αS oligomer); or 1 ng/mL, 10 ng/mL, 100 ng/mL, and 1 μg/mL of thesynthetic soluble oligomeric αS protein seed. αS-PMCA general procedure:Solutions of 100 μg/mL αS seed-free αS in PBS, pH 7.4 (200 μL totalvolume) were placed in opaque 96-wells plates and incubated alone or inthe presence of the indicated concentrations of synthetic αS aggregatesor 40 μL of CSF aliquots. Samples were incubated in the presence of 5 μMThioflavin T (ThT) and subjected to cyclic agitation (1 min at 500 rpmfollowed by 29 min without shaking) using an Eppendorf thermomixer, at aconstant temperature of 22° C. At various time points, ThT fluorescencewas measured in the plates at 485 nm after excitation at 435 nm using aplate spectrofluorometer. FIG. 13A is a graph of Thioflavin Tfluorescence as a function of time, showing the detection of αS seeds byPD-PMCA, using the indicated concentration of synthetic solubleoligomeric αS protein seeds. The peptide concentration, temperature andpH of the buffer were monitored to control the extent of the lag phaseand reproducibility among experiments. Aggregation of monomeric αSprotein was observed in the presence of 1 ng/mL, 10 ng/mL, 100 ng/mL,and 1 μg/mL αS of the synthetic soluble oligomeric αS protein seed.

EXAMPLE 13B: The time to reach 50% aggregation as a function of amountsof αS seeds added was determined using the samples in EXAMPLE 1A. FIG.13B is a graph showing time to reach 50% aggregation plotted as afunction of amounts of αS seeds added.

Example 14: αS-PMCA Detects Oligomeric αS in the Cerebrospinal Fluid ofPd Patients

Detection of seeding activity in human CSF samples from controls and PDpatients was performed by PD-PMCA. Purified seed free alpha-synuclein(100 μg/mL) in PBS, pH 7.4 was allowed to aggregate at 37° C. withshaking at 500 rpm in the presence of CSF from human patients withconfirmed PD, AD or non-neurodegenerative neurological diseases (NND).The extend of aggregation was monitored by Thioflavin fluorescence at485 nm after excitation at 435 nm using a plate spectrofluorometer.

Aliquots of CSF were obtained from PD patients, cognitively normalindividuals affected by non-degenerative neurological diseases (NND),and patients affected by Alzheimer's disease (AD). Test CSF samples wereobtained from patients with the diagnosis of probable PD as defined bythe DSM-IV and determined using a variety of tests, including routinemedical examination, neurological evaluation, neuropsychologicalassessment, and magnetic resonance imaging. CSF samples were collectedin polypropylene tubes following lumbar puncture at the L4/L5 or L3/L4interspace with atraumatic needles after one night fasting. The sampleswere centrifuged at 3,000 g for 3 min at 4° C., aliquoted and stored at−80° C. until analysis. CSF cell counts, glucose and proteinconcentration were determined. Albumin was measured by ratenephelometry. To evaluate the integrity of the blood brain barrier andthe intrathecal IgG production, the albumin quotient (CSF albumin/serumalbumin)×10³ and the IgG index (CSF albumin/serum albumin)/(CSFIgG/serum IgG) were calculated. The study was conducted according to theprovisions of the Helsinki Declaration and was approved by the EthicsCommittee.

The experiments as well as the initial part of the analysis wereconducted blind. FIG. 14 is a graph of αS oligomerization versus time,measured as a function of ThT fluorescence labeling, showing the averagekinetics of αS aggregation of representative samples from the PD, AD,and NND groups.

The results indicate that CSF from PD patients significantly acceleratesαS aggregation as compared to control CSF (P<0.001). The significance ofthe differences in αS aggregation kinetics in the presence of human CSFsamples was analyzed by one-way ANOVA, followed by the Tukey's multiplecomparison post-test. The level of significance was set at P<0.05. Thedifferences between PD and samples from the other two groups were highlysignificant with P<0.001 (***).

Example 15: Specificity of Immuno Capturing

FIG. 15 shows Table 3, demonstrating the ability of different sequenceor conformational antibodies to capture αS oligomers. The capacity tocapture oligomers was measured by spiking synthetic αS oligomers inhealthy human blood plasma and detection by αS-PMCA. The first columnshows various antibodies tested and corresponding commercial sources.The second column lists the epitope recognition site on the αS proteinof the diverse sequence antibodies used in this study. The third columnindicates the observed ability of specific antibodies to capture the αSoligomers. The symbols indicate that the detection limits using thedifferent antibodies were: <12 fmol (+++); between 10-100 fmol (++); >1pmol (+) and not significantly higher than without capturing reagent(−). Alpha/beta-synuclein antibody N-19 (N-terminal epitope) andalpha-synuclein antibody C-20-R (C-terminal epitope) showed the bestresults; and alpha-synuclein antibody 211 (epitope: amino acids 121-125)showed very good results; alpha-synuclein antibody 204 (epitope:fragment 1-130) showed good results; and 16 ADV Mouse IgG1(conformational epitope) showed no result.

Example 16: Solid Phase Immuno Capturing

FIGS. 16A and 16B are schematic representations of two solid phasemethods used to capture soluble, misfolded αS protein from complexsamples such as blood plasma. Strategy 1 employed ELISA platespre-coated with specific antibodies bound to a solid phase on the ELISAplate. After washing the plates, the αS-PMCA reaction was carried out inthe same plates. Strategy 2 used magnetic beads as the solid phasecoated with specific antibodies. This approach provided concentration ofthe samples.

Example 17: αS-PMCA for the Detection of α-Synuclein Oligomers Spiked inHuman Blood Plasma

Immunoprecipitation of α-Synuclein oligomers from human blood plasma wasperformed by anti-α-Synuclein antibody-coated beads (Dynabeads) and aseeding aggregation assay using α-Synuclein monomers as seedingsubstrate along with thioflavin-T for detection. The anti-α-Synucleincoated beads (1×10⁷ beads) were incubated with human blood plasma (500μL) with α-Synuclein seeds (+0.2 μg Seed) and without α-Synuclein seeds(−Seed). After immunoprecipitation, the beads were re-suspended in 20μL, of reaction buffer (1×PBS), and 10 μL of beads were added to eachwell of a 96-well plate. The aggregation assay was performed by addingα-Synuclein monomers (200 μg/mL) and thioflavin-T (5 μM). The increasein florescence was monitored by a fluorimeter using an excitation of 435nm and emission of 485 nm. FIG. 17A illustratesimmunoprecipitation/aggregation results with N-19 antibody in bloodplasmas with and without seed. FIG. 17B illustratesimmunoprecipitation/aggregation results with 211 antibody in bloodplasmas with and without seed. FIG. 17C illustratesimmunoprecipitation/aggregation results with C-20 antibody in bloodplasmas with and without seed.

Example 18: αS-PMCA Detects Oligomeric αS in the Cerebrospinal Fluid ofPatients Affected by Pd and Multiple System Atrophy with HighSensitivity and Specificity

To study the efficiency of αS-PMCA for biochemical diagnosis of PD andrelated α-synucleinopathies, such as multiple system atrophy (MSA),tests were performed on CSF from many patients affected by thesediseases as well as controls affected by other diseases. FIGS. 18A, 18B,and 18C show detection of seeding activity in human CSF samples fromcontrols and patients affected by PD and MSA, respectively, usingαS-PMCA. Purified seed free alpha-synuclein (100 μg/mL) in buffer MES,pH 6.0 was allowed to aggregate at 37° C. with shaking at 500 rpm in thepresence of CSF from human patients and controls. The extent ofaggregation was monitored by Thioflavin T fluorescence at 485 nm afterexcitation at 435 nm using a plate spectrofluorometer.

Test CSF samples were obtained from patients with the diagnosis ofprobable PD and MSA as defined by the DSM-IV and determined using avariety of tests, including routine medical examination, neurologicalevaluation, neuropsychological assessment, and magnetic resonanceimaging. CSF samples were collected in polypropylene tubes followinglumbar puncture at the L4/LS or L3/L4 interspace with atraumatic needlesafter one night fasting. The samples were centrifuged at 3,000 g for 3min at 4° C., aliquoted and stored at −80° C. until analysis. CSF cellcounts, glucose and protein concentration were determined. Albumin wasmeasured by rate nephelometry. The study was conducted according to theprovisions of the Helsinki Declaration and was approved by the EthicsCommittee.

The experiments as well as the initial part of the analysis wereconducted blind. FIGS. 18A, 18B, and 18C are graphs of αS aggregationversus time, measured as a function of ThT fluorescence labeling,showing the average kinetics of αS aggregation, respectively, forcontrols and two representative samples from the PD and MSA groups.

The results indicate that CSF from PD patients significantly acceleratesαS aggregation as compared to control CSF (P<0.001). The significance ofthe differences in αS aggregation kinetics in the presence of human CSFsamples was analyzed by one-way ANOVA, followed by the Tukey's multiplecomparison post-test. The level of significance was set at P<0.05. Thedifferences between PD and samples from the other two groups were highlysignificant with P<0.001 (***).

The outcome of the overall set of 29 PD or MSA samples and 41 controlswas that 26 of the 29 PD or MSA samples were positive, whereas 3 of the41 control samples were positive, which corresponded to a 90%sensitivity and 93% specificity.

Example 19: Synthesis of Full-Length 4R Tau Protein and Seeds

FIG. 19 is a flow chart showing the preparation and purification ofrecombinant full-length 4R tau protein. A gene for hTau40 wastransfected into E. coli and incubated under standard conditions toexpress the hTau40. After a period of growth, the E. coli cells werepelted, lysed, heat treated, and precipitated with ammonium sulfate toproduce a crude product. The crude product was subjected to cationexchange chromatography, dialysis, then concentrated and the bufferexchanged. Cut-off filtration at a mass of 100 kDa was employed tofurther purify the hTau40. The yield of the purified hTau 40 was 20 mg/Lof bacterial culture. Full-length 4R Tau seeds were then prepared byincubating hTau 40 monomer with 12.5 μM heparin in 10 mM HEPES pH 7.4,100 mM NaCl for 3 days at 37° C. using cyclic agitation (1 min shakingat 500 rpm followed by 29 min without shaking).

Example 20a: Tau PMCA

A Tau-PMCA assay was performed on 96 well plates using 12.5 μM Taumonomer, 1.25 μM heparin, 5 μM Thioflavin T, using cyclic agitation (1min shaking at 500 rpm followed by 29 min without shaking). Seeds wereadded to the wells in amounts of 12.5 pmol, 1.25 pmol, 125 fmol, 12.5fmol, and 1.25 fmol. Controls were performed without seeds. Aggregationwas followed over time by ThT fluorescence using a platespectrofluorometer (excitation: 435; emission: 485). FIG. 20A is a graphof aggregation in % for the various initial amounts of seeds and thecontrol. The values in FIG. 20A are the mean of two replicates, with theerror bars indicating standard deviation. FIG. 20B is a graph of T₅₀,the time to 50% aggregation as measured by ThT fluorescence versus thelog of the amount of oligomeric tau seeds in fmol.

Example 20B: Tau PMCA

For optimization of the tau-PMCA assay, full-length human Tau40 thatincludes four imperfect tandem microtubule binding repeats (4R). Tauoligomers were generated by incubation of full-length Tau (50 μM) in thepresence of heparin (12.5 μM) for 3 days at 37° C. Seeds werecharacterized by ability to seed tau aggregation, binding to thioflavinT, western blot and electron microscopy. The preformed aggregates wereused to nucleate and induce the aggregation of Tau. For the assay,seed-free monomeric tau (15 μM) in 10 mM HEPES pH 7.4, 100 mM NaClcontaining 3 μM of heparin in the absence or the presence of differentquantities of synthetic seeds was subjected to cycles of tau-PMCA byincubating at 20° C. for 29.5 min followed by shaking for 30 sec at 500rpm. Under these conditions, Tau was only observed to aggregate in thepresence of preformed seeds and the kinetic of aggregation was dependenton the amount of seeds added. Importantly, the PMCA signal was observedto be directly proportional to the amount of seeds added to thereaction. This assay corresponded to a detection threshold of 0.125 pgof oligomeric tau. This detection threshold corresponds to −2 atto-mol,based on the molecular weight of the tau monomer, or 0.15 atto-mol,based on the molecular weight of a 12-mer oligomer as a proxy foraverage oligomer size.

Example 20C: Tau PMCA

A further Tau-PMCA assay was performed using full-length Tau seedsprepared by incubating Tau monomer with 12.5 μM heparin in 10 mM HEPESpH 7.4, 100 mM NaCl for 3 days at 37° C. with shaking. The assay wasperformed on 96 well plates using 12.5 μM Tau monomer, 1.25 μM heparin,and 5 μM Thioflavin T, using cyclic agitation (1 min shaking at 500 rpmfollowed by 29 min without shaking). FIG. 20C is a graph of aggregationfollowed over time by ThT fluorescence using a plate spectrofluorometer(excitation: 435; emission: 485). FIG. 20C shows the mean and SD of tworeplicates. FIG. 20D is a graph of the relationship between the quantityof tau oligomers and the Tau-PMCA signal (time to reach 50%aggregation).

Example 20D: Tau PMCA is Reproducible

A large scale experiment was conducted to evaluate the robustness andreproducibility of the tau-PMCA assay to analyze the performance at fourdifferent times (0, 14, 28 and 30 days) with or withoutfreezing/thawing. Two different set of synthetic seeds and fivedifferent concentrations of synthetic seeds (1250, 125, 12.5, 1.25 and0.125 pg of seeds) were employed, spiked either in buffer or controlCSF. Each sample was run in triplicate. The experiment encompassedseveral steps, including the large-scale expression and purification oftau in quantities needed to perform all experiments, quality control ofthe material produced, generation and characterization of synthetic tauoligomeric seeds and the tau-PMCA experiments to investigate assayprecision and reproducibility in buffer and in the biological matrix(CSF). In total the experiment employed 32 different conditions (2different seeds×4 time points x: 2 manners of dilution (freezing or notfreezing)×2 different matrices (buffer or CSF)). Since all conditionswere tested with five different concentrations of oligomeric seeds andeach was done in triplicate, the entire experiment involved 480 wells.The protein concentration, buffer and PMCA conditions were the same asEXAMPLE 20B. From the 32 conditions tested only one gave results thatwere slightly significantly different from the others, indicating highprecision and reproducibility. FIGS. 20E-20L are a series of graphs thatdisplay the aggregation results based on ThT fluorescence of 8 of theconditions tested, including 4 different time points (0, 7, 14 and 30days) with samples subjected to freezing and thawing or not and in thepresence of buffer or CSF, and two different seed preparations (FIGS.20E-20H and FIGS. 20I-20L). FIGS. 20E-20L demonstrate that the resultsobtained are very similar between the triplicates, different timepoints, and distinct seeds. Data correspond to average±standard error oftriplicate samples. Tau substrate in the absence of seeds was notobserved to aggregate under any condition within the time in whichexperiments were done.

To analyze the reproducibility of the assay, T₅₀ values (time to reach50% aggregation) for the experiments in the presence of 1250 pg of Tauseeds. The Tso values for the experiments done at different days, withone of two seed preparations A or B and using fresh or frozen seeds didnot show any statistically significant difference and an average Tso of71.5±1.8 h was obtained. Similar non-significant differences wereobserved for the studies done in the presence of all the other seedconcentrations or for the experiments done in buffer. FIG. 20M is atable of T₅₀ values showing reproducibility across 16 differentconditions. All values were analyzed by one way ANOVA, followed by Tukeymultiple comparison test.

Example 20E: Tau PMCA is Specific

The tau PMCA assay was investigated for specificity, particularly forthe ability to detect aggregates composed of other amyloidogenicproteins. Aβ and αSyn oligomeric species were prepared and used tocross-seed monomeric tau. FIG. 20N is a graph of ThT fluorescence vstime for the tau assay seeded with 1 pm of tau, Aβ40, AB42, His αSyn, HuαSyn, and no seeds. FIG. 20N shows that no significant signal wasdetectable in the presence of Aβ or αSyn seeds and no signal wasdetected before about 100 h, even when the concentration of theseparticles was relatively high (equivalent to 2 ng of tau seeds). TheseAβ are αSyn seeds are very efficient in inducing aggregation in therespective Aβ- or αSyn-PMCA assays described in preceding EXAMPLES.These results indicate that under the conditions and concentrations usedthere is no cross-seeding between other protein aggregates and thattau-PMCA is specific for detecting tau oligomers.

Example 21a: Tau PMCA Detects Tau in Human CSF

Human CSF samples from AD patients (7 cases), 5 other Tauopathies (1FTD,2PSP, 2CBD), people affected by mild cognitive impairment (MCI) andcontrols affected by other neurological diseases (7 samples) wereanalyzed by Tau-PMCA. FIG. 21A is a graph showing ThT fluorescence at447 h of incubation, in which most samples have reached the maximumfluorescence. Positive controls used samples of healthy CSF spiked withsynthetic Tau oligomers (12.5 fmol). Negative controls correspond tosamples of healthy CSF without Tau seeds. FIG. 21A shows that patientswith AD, other tauopathies, and MCI showed Tau aggregation significantlyabove the negative control and consistent with the positive control. 6of the 7 control patients with other neurological diseases wereconsistent with the negative control. One control patients in the otherneurological disease group showed maximum fluorescence consistent with atauopathy. This may indicate an undiagnosed tauopathy in that patient,or alternatively, inadvertent contamination.

Example 21B: Tau PMCA Detects Tau in Human CSF

Human CSF samples from 11 patients affected by AD, 11 from othertauopathies (4 PSP, 1 FTD, 5 CBD and 1 CTE) and 7 controls affected fromunrelated neurological disorders were examined. Positive controls wereprepared by spiking CSF with 20 ng of recombinant tau oligomers.Negative controls were healthy CSF without tau seeds. FIG. 21B is agraph of fluorescence signals for samples from patients with AD or othertauopathies for tau-PMCA comparable to that observed in samplescontaining recombinant tau oligomers. Consequently, samples frompatients with AD or other tauopathies were able to accelerate tauaggregation. Conversely, 6 out of 7 of the controls produced a lowsignal in tau-PMCA, with values equivalent to those observed in CSFwithout seeds. Despite the small sample size, the differences betweencontrols and patients were statistically significant. These positiveresults indicate that tau-PMCA is capable of detecting tau aggregates inCSF of patients. FIG. 21B shows the maximum ThT fluorescence, expressedas arbitrary units. Differences were analyzed by one-way ANOVA followedby the Tukey's multiple comparison post-test. ** P<0.01.

Example 22: Tau PMCA Detects Tau in Human CSF

The performance of Tau-PMCA assay was examined in the presence ofrepresentative CSF samples from a control, and patients affected by AD,FTD (frontotemporal dementia), CBD (corticobasal degeneration), and PSP(progressive supranuclear palsy). The Tau-PMCA assay was performed on 96well plates using 12.5 μM Tau monomer, 1.25 μM heparin, 5 μM ThioflavinT, using cyclic agitation (1 min shaking at 500 rpm followed by 29 minwithout shaking). Aggregation was followed over time by ThT fluorescenceusing a plate spectrofluorometer (excitation: 435; emission: 485). FIG.22 is a graph showing aggregation % based on ThT versus time. Thevarious tauopathies differed in T₅₀, amplification rate, andamplification extent. For example, the T₅₀ of PSP and AD samples wasabout the same at 150 h, while the PSP sample appeared to have a shorterlag phase, a lower amplification rate, and a lower extent ofamplification compared to AD. CBD appeared to have a T₅₀ of about 175 h,with a lower amplification rate, and a lower extent of amplificationcompared to both AD and PSP. FTD appeared to have a T₅₀ of about 210 h,with a higher amplification rate, and a lower extent of amplificationcompared to each of AD, PSP, and CBD. The control CSF sample had asimilar Tso and amplification rate compared to FTD, with a far lowerextent of amplification. The amplification in the control CSF sample maybe due to spontaneous (seed-free) amplification, inadvertentcontamination, or an undiagnosed tauopathy with somewhat similarkinetics to FTD.

Discussion

The present tau-PMCA may provide various advantages. For example,embodiments of the present invention may detect the tau misfoldedprotein directly, by contrast with known indirect measures such asnon-pathogenic biomarkers, measurement of the total pool of tau of whichonly a small fraction forms the synapto-toxic oligomeric aggregates, ormeasurement of variously phosphorylated species of tau. In variousembodiments, the present invention detects the misfolded tau oligomersthat seed tau misfolding and are believed to contribute to spreading thedamage in the brain during the disease.

To the extent that the term “includes” or “including” is used in thespecification or the claims, it is intended to be inclusive in a mannersimilar to the term “comprising” as that term is interpreted whenemployed as a transitional word in a claim. Furthermore, to the extentthat the term “or” is employed (e.g., A or B) it is intended to mean “Aor B or both.” When the applicants intend to indicate “only A or B butnot both” then the term “only A or B but not both” will be employed.Thus, use of the term “or” herein is the inclusive, and not theexclusive use. See Bryan A. Garner, A Dictionary of Modern Legal Usage624 (2d. Ed. 1995). Also, to the extent that the terms “in” or “into”are used in the specification or the claims, it is intended toadditionally mean “on” or “onto.” To the extent that the term“selectively” is used in the specification or the claims, it is intendedto refer to a condition of a component wherein a user of the apparatusmay activate or deactivate the feature or function of the component asis necessary or desired in use of the apparatus. To the extent that theterm “operatively connected” is used in the specification or the claims,it is intended to mean that the identified components are connected in away to perform a designated function. To the extent that the term“substantially” is used in the specification or the claims, it isintended to mean that the identified components have the relation orqualities indicated with degree of error as would be acceptable in thesubject industry.

As used in the specification and the claims, the singular forms “a,”“an,” and “the” include the plural unless the singular is expresslyspecified. For example, reference to “a compound” may include a mixtureof two or more compounds, as well as a single compound.

As used herein, the term “about” in conjunction with a number isintended to include ±10% of the number. In other words, “about 10” maymean from 9 to 11.

As used herein, the terms “optional” and “optionally” mean that thesubsequently described circumstance may or may not occur, so that thedescription includes instances where the circumstance occurs andinstances where it does not.

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group. As will beunderstood by one skilled in the art, for any and all purposes, such asin terms of providing a written description, all ranges disclosed hereinalso encompass any and all possible sub-ranges and combinations ofsub-ranges thereof Δny listed range can be easily recognized assufficiently describing and enabling the same range being broken downinto at least equal halves, thirds, quarters, fifths, tenths, and thelike. As a non-limiting example, each range discussed herein can bereadily broken down into a lower third, middle third and upper third,and the like. As will also be understood by one skilled in the art alllanguage such as “up to,” “at least,” “greater than,” “less than,”include the number recited and refer to ranges which can be subsequentlybroken down into sub-ranges as discussed above. Finally, as will beunderstood by one skilled in the art, a range includes each individualmember. For example, a group having 1-3 cells refers to groups having 1,2, or 3 cells. Similarly, a group having 1-5 cells refers to groupshaving 1, 2, 3, 4, or 5 cells, and so forth. While various aspects andembodiments have been disclosed herein, other aspects and embodimentswill be apparent to those skilled in the art.

As stated above, while the present application has been illustrated bythe description of embodiments thereof, and while the embodiments havebeen described in considerable detail, it is not the intention of theapplicants to restrict or in any way limit the scope of the appendedclaims to such detail. Additional advantages and modifications willreadily appear to those skilled in the art, having the benefit of thepresent application. Therefore, the application, in its broader aspects,is not limited to the specific details, illustrative examples shown, orany apparatus referred to. Departures may be made from such details,examples, and apparatuses without departing from the spirit or scope ofthe general inventive concept.

The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

1. A method for determining a presence or absence in a sample of a firstmisfolded protein aggregate, the method comprising: performing a firstprotein misfolding cyclic amplification (PMCA) procedure, the first PMCAprocedure comprising: forming a first incubation mixture by contacting afirst portion of the sample with a first substrate protein, the firstsubstrate protein comprising 4R tau; conducting an incubation cycle twoor more times under conditions effective to form a first amplified,misfolded protein aggregate, each incubation cycle comprising:incubating the first incubation mixture effective to cause misfoldingand/or aggregation of at least a portion of the first substrate proteinin the presence of the first misfolded protein aggregate; disrupting thefirst incubation mixture effective to form the first amplified,misfolded protein aggregate; and determining the presence or absence inthe sample of the first misfolded protein aggregate by analyzing thefirst incubation mixture for the presence or absence of the firstamplified, misfolded protein aggregate, the first misfolded proteinaggregate comprising the first substrate protein and the firstamplified, misfolded protein aggregate comprising the first substrateprotein.
 2. The method of claim 1, comprising determining the presencein the sample of the first misfolded protein aggregate, the firstmisfolded protein aggregate being misfolded 4R tau aggregate.
 3. Themethod of claim 1, further comprising determining the presence orabsence in the sample of at least a second misfolded protein aggregate.4. The method of claim 3, further comprising performing at least asecond PMCA procedure to determine the presence or absence in the sampleof at least the second misfolded protein aggregate, comprising: forminga second incubation mixture by contacting a second portion of the samplewith a second substrate protein, the second substrate protein beingsubject to pathological misfolding and/or aggregation in vivo to formthe second misfolded protein aggregate; conducting an incubation cycletwo or more times under conditions effective to form a second amplified,misfolded protein aggregate, each incubation cycle comprising:incubating the second incubation mixture effective to cause misfoldingand/or aggregation of at least a portion of the second substrate proteinin the presence of the second misfolded protein aggregate; disruptingthe second incubation mixture effective to form the second amplified,misfolded protein aggregate; and determining the presence or absence inthe sample of the second misfolded protein aggregate by analyzing thesecond incubation mixture for the presence or absence of the secondamplified, misfolded protein aggregate, the second misfolded proteinaggregate comprising the second substrate protein and the secondamplified, misfolded protein aggregate comprising the second substrateprotein, the second substrate protein comprising one of: amyloid-beta(Aβ), alpha synuclein, and 3R tau.
 5. The method of claim 4, the secondsubstrate protein comprising 3R tau, the method further comprisingdetermining a ratio of the 4R tau and the 3R tau in the sample ofbetween about 1:99 and about 99:1.
 6. The method of claim 1, the samplebeing taken from a subject, further comprising determining or diagnosingthe presence or absence of a tauopathy in the subject according to thepresence or absence of the first misfolded protein aggregate in thesample.
 7. The method of claim 6, further comprising characterizing anidentity of the tauopathy by analyzing the first amplified, misfoldedprotein aggregate or one or more corresponding PMCA kinetic parametersthereof for a signature of at least one of: Alzheimer's disease (AD),Parkinson's Disease (PD), Progressive Supranuclear Palsy (PSP),FrontoTemporal Dementia (FTD), Corticobasal degeneration (CBD), Mildcognitive impairment (MCI), Argyrophilic grain disease (AgD) TraumaticBrain Injury (TBI), Chronic Traumatic Encephalopathy (CTE), and DementiaPugilistica (DP).
 8. The method of claim 7, characterizing the identityof the tauopathy comprising using one or more of: an antibody selectivefor a conformational epitope of a tauopathy-specific misfolded tauprotein aggregate; an indicator selective for the tauopathy-specificmisfolded tau protein aggregate; a spectrum characteristic of thetauopathy-specific misfolded tau protein aggregate; a proteolyticresistance of the tauopathy-specific misfolded tau protein aggregate;and a stability to denaturation of the tauopathy-specific misfolded tauprotein aggregate.
 9. The method of claim 1, the sample being taken froma subject characterized by one of: exhibiting no clinical signs ofdementia according to cognitive testing; exhibiting no cortex plaques ortangles according to contrast imaging; and exhibiting clinical signs ofdementia according to cognitive testing, further comprising determiningor diagnosing the presence or absence of a tauopathy in the subjectaccording to the presence or absence of the first misfolded proteinaggregate in the sample.
 10. The method of claim 1, comprising preparingthe first incubation mixture characterized by at least one concentrationof: the first substrate protein of less than about 20 μM; heparin ofless than about 75 μM; NaCl of less than about 190 mM; and Thioflavin Tof less than about 9.5 μM.
 11. The method of claim 1, comprisingpreparing or maintaining the first incubation mixture characterized byone or more of: the first substrate protein at a concentration betweenabout 0.001 μM and about 2000 μM; heparin at a concentration betweenabout 0.001 μM and about 75 μM; comprising a buffer composition of oneor more of: Tris-HCL, PBS, MES, PIPES, MOPS, BES, TES, and HEPES, thebuffer composition at a total concentration of between about 1 μM andabout 1 M; comprising a salt composition at a total concentration ofbetween about 1 μM and about 1 M; a pH of between about 5 and about 9;comprising an indicator at a total concentration of between about 1 nMand about 1 mM; and a temperature between about 5° C. and about 60° C.12. The method of claim 1: further comprising contacting an indicator ofthe first misfolded protein aggregate to the first incubation mixture,the indicator of the first misfolded protein aggregate beingcharacterized by an indicating state in the presence of the firstmisfolded protein aggregate and a non-indicating state in the absence ofthe first misfolded protein aggregate; and wherein the determining thepresence of the first misfolded protein aggregate in the samplecomprises detecting the indicating state of the indicator of the firstmisfolded protein aggregate.
 13. The method of claim 1, the detectingthe first misfolded protein aggregate comprising one or more of: aWestern Blot assay; a dot blot assay; an enzyme-linked immunosorbentassay (ELISA); a fluorescent protein/peptide binding assay; a thioflavinbinding assay, a Congo Red binding assay; a sedimentation assay;electron microscopy; atomic force microscopy; surface plasmon resonance;spectroscopy; contacting the first incubation mixture with a protease,and detecting the first misfolded protein aggregate using anti-misfoldedprotein antibodies or antibodies specific for a misfolded tau aggregatein one or more of: a Western Blot assay, a dot blot assay, and an ELISA.14. The method of claim 1, the sample characterized by one or more of:comprising one or more of amniotic fluid; bile; blood; cerebrospinalfluid; cerumen; skin; exudate; feces; gastric fluid; lymph; milk; mucus;mucosal membrane; peritoneal fluid; plasma; pleural fluid; pus; saliva;sebum; semen; sweat; synovial fluid; tears; and urine; derived fromcells or tissue of one or more of: skin, brain, heart, liver, pancreas,lung, kidney, gastro-intestine, nerve, mucous membrane, blood cell,gland, and muscle; and each portion of the sample characterized by avolume from about 1 μL to about 1000 μL.
 15. The method of claim 1,further comprising obtaining the sample from a subject, the subjectbeing one or more of: at risk of a tauopathy, having the tauopathy, andunder treatment for the tauopathy.
 16. The method of claim 15, thesubject being treated with a tauopathy modulating therapy, furthercomprising: comparing the amount of the first misfolded proteinaggregate in the sample to an amount of the first misfolded proteinaggregate in a comparison sample, the sample and the comparison samplebeing taken from the subject at different times over a period of timeunder the tauopathy modulating therapy; and determining the subject isone of: responsive to the tauopathy modulating therapy according to achange in the first misfolded protein aggregate over the period of time,or non-responsive to the tauopathy modulating therapy according tohomeostasis of the first misfolded protein aggregate over the period oftime.
 17. The method of claim 1, further comprising selectivelyconcentrating the first misfolded protein aggregate in one or more ofthe sample and the first incubation mixture.
 18. The method of claim 1,the disrupting the first incubation mixture comprising one or more of:sonication, stirring, cyclic agitation, shaking, freezing/thawing, laserirradiation, autoclave incubation, high pressure, and homogenization.19. The method of claim 1, comprising: contacting the sample with athioflavin and a molar excess of the first substrate protein to form thefirst incubation mixture, the molar excess being greater than an amountof the first substrate protein included in the first misfolded proteinaggregate in the sample; conducting the incubation cycle two or moretimes effective to form the first amplified, misfolded proteinaggregate, each incubation cycle comprising: incubating the firstincubation mixture effective to cause misfolding and/or aggregation ofthe first substrate protein in the presence of the first misfoldedprotein aggregate; shaking the first incubation mixture effective toform the first amplified, misfolded protein aggregate; and determiningthe presence of the first misfolded protein aggregate in the sample bydetecting a fluorescence of the thioflavin corresponding to the firstmisfolded protein aggregate.
 20. The method of claim 1, provided thesample excludes tau fibrils.